"The Harton Colliery Experiment: I had long wished to repeat the experiment which I had attempted unsuccessfully in 1826 and 1828, of determining by pendulum-vibrations the measure of gravity at the bottom of a mine. Residing near Keswick this summer, and having the matter in my mind, I availed myself of an introduction from Dr Leitch to some gentlemen at South Shields, for inspection of the Harton Colliery. I judged that it would answer pretty well. I find that on Aug. 11th I wrote to Mr Anderson (lessee of the mine), and on the same day to the Admiralty requesting authority to employ a Greenwich Assistant, and requesting L100 for part payment of expenses. On August 16th the Admiralty assent. There were many preparations to be made, both personal and instrumental. My party consisted of Dunkin (Superintendant), Ellis, Criswick, Simmons, Pogson, and Ruemker: I did not myself attend the detail of observations. The observations began on Oct. 2nd and ended on Oct. 21st: supplementary observations were subsequently made at Greenwich for examining the coefficient of temperature-correction. On Oct. 24th I gave a Lecture at South Shields on the whole operation. In 'Punch' of Nov. 18th there was an excellent semi-comic account of the experiment, which as I afterwards found was written by Mr Percival Leigh."

Of private history: "On Jan. 18th I returned from Playford. From Mar. 10th to 13th I was at Deal, and visited Sir John Herschel at Hawkhurst.—From June 28th to Aug. 7th I was staying with my family at The Grange, in Borrowdale near Keswick: and also made an expedition to Penrith, Carlisle, Newcastle, Jarrow, &c.; and descended the Harton Pit.—In September and also in October I was at South Shields on the Harton Experiments.—From Dec. 14th to 18th I was at Cambridge, and on the 26th I went to Playford."

The following letter, written in answer to a lady who had asked him to procure permission from Lord Rosse for her to observe with his telescope, is characteristic:

ROYAL OBSERVATORY, GREENWICH. 1854, September 20.

DEAR MADAM,

The state of things with regard to Lord Rosse's Telescope is this. If a night is fine, it is wanted for his use or for the use of professional astronomers. If it is not fine, it is of no use to anybody. Now considering this, and considering that the appropriation of the telescope on a fine night to any body but a technical astronomer is a misapplication of an enormous capital of money and intellect which is invested in this unique instrument—it is against my conscience to ask Lord Rosse to place it at the service of any person except an experienced astronomer. No introduction, I believe, is necessary for seeing it in the day-time. The instrument stands unenclosed in the Castle Demesne, to which strangers are admitted without question, I believe...............

Faithfully yours, G.B. AIRY.

1855

"On May 9th it was notified to me (I think through the Hydrographer) that the Admiralty were not unwilling to increase my salary. I made application therefore; and on Jan. 21st 1856 Sir Charles Wood notified to me that the Admiralty consented to have it raised from L800 to L1000.—In the Report to the Board of Visitors it appears that 'At the instance of the Board of Trade, acting on this occasion through a Committee of the Royal Society, a model of the Transit Circle (with the improvement of perforated cube, &c. introduced in the Cape Transit Circle) has been prepared for the Great Exhibition at Paris.'—Under the head of Reduction of Astronomical Observations it is stated that 'During the whole time of which I have spoken, the galvanic-contact method has been employed for transits, with the exception of a few days, when the galvanic apparatus was out of order. From the clock errors, I have deduced the personal equations of the observers in our usual way.... The result is that the magnitude of the personal equations in the galvanic-touch method is not above half of that in the eye and ear method.'—With regard to the Reduction of the Magnetical Observations, 'I have not yet felt sufficiently satisfied with any proposed method of discussing the magnetic results to devote any time to their further treatment.'—'The Time-Signal Ball at Deal was brought into regular use at the beginning of the present year. In a short time, however, its action was interrupted, partly by derangement of the apparatus, and partly by the severity of the weather, which froze the sulphuric acid to the state of jelly. I sent an assistant and workman to put it in order, and since that time it has generally acted very well.—Application has been made to me from one of the important offices of Government (the Post Office) for the galvanic regulation of their clocks.—On considering the risks to which various galvanic communications are liable, and the financial necessity for occupying wires as little as possible, I perceived that it was necessary to devise constructions which should satisfy the following conditions. First, that a current sent once a day should suffice for adjusting the clock, even if it had gone ten or more seconds wrong. Secondly, that an occasional failure of the current should not stop the clock. I have arranged constructions which possess these characters, and the artist (Mr C. Shepherd) is now engaged in preparing estimates of the expense. I think it likely that this may prove to be the beginning of a very extensive system of clock regulation."—With respect to the operations for determining the longitude of Paris, it is stated that, "The whole number of days of signal transmission was eighteen, and the whole number of signals transmitted was 2530. The number of days considered available for longitude, in consequence of transits of stars having been observed at both Observatories, was twelve, and the number of signals was 1703. Very great care was taken on both sides, for the adjustments of the instruments. The resulting difference of longitude, 9m. 20.63s., is probably very accurate. It is less by nearly 1s. of time than that determined in 1825 by rocket-signals, under the superintendance of Sir John Herschel and Col. Sabine. The time occupied by the passage of the galvanic current appears to be 1/12th of a second."—With regard to the Pendulum Experiments in the Harton Colliery, after mentioning that personal assistance had been sought and obtained from the Observatories of Cambridge, Oxford, Durham, and Red Hill, the Report states that "The experiments appear to have been in every point successful, shewing beyond doubt that gravity is increased at the depth of 1260 feet by 1/10000th part. I trust that this combination may prove a valuable precedent for future associations of the different Observatories of the kingdom, when objects requiring extensive personal organization shall present themselves."—On Oct. 18th the Astronomer Royal printed an Address to the Individual Members of the Board of Visitors on the subject of a large new Equatoreal for the Observatory. After a brief statement of the existing equipment of the Observatory in respect of equatoreal instruments, the Address continues thus: "It is known to the Visitors that I have uniformly objected to any luxury of extrameridional apparatus, which would materially divert us from a steady adherence to the meridional system which both reason and tradition have engrafted on this Observatory. But I feel that our present instruments are insufficient even for my wishes; and I cannot overlook the consideration that due provision must be made for future interests, and that we are nearer by twenty years to the time when another judgment must decide on the direction which shall be given to the force of the Observatory."—"In August I had some correspondence about the Egyptian wooden astronomical tablets with Mr Gresswell and others: they were fully examined by Mr Ellis.—In this year I was much engaged on schemes for compasses, and in June I sent my Paper on Discussions of Ships' Magnetism to the Royal Society.—On Dec. 6th the mast of the Observatory time-ball broke, and the Ball fell in the Front Court.—On Aug. 4th my valued friend Mr Sheepshanks died; and on Aug. 14th I went to London to see the Standard Bars as left by him. Afterwards, on Oct. 25th I went to Reading to collect the papers about Standards left by Mr Sheepshanks.—I made a mechanical construction for Euclid I. 47, with which I was well satisfied.—On Apr. 13th I joined a deputation to the Chancellor of the Exchequer (Sir G. Cornewall Lewis) on Decimal Coinage."

Of private history: "I was at Playford for a large part of January.—On Mar, 26th I went to Reading, to visit Mr Sheepshanks, and afterwards to Silchester and Hereford.—On June 21st I went with my wife and two eldest sons to Edinburgh and other places in Scotland, but residing principally at Oban, where I hired a house. Amongst other expeditions, I and my son Wilfrid went with the 'Pharos' (Northern Lights Steamer) to the Skerry Vohr Lighthouse, &c. I also visited Newcastle, &c., and returned to Greenwich on Aug. 2nd.—From Oct. 12th to 17th I was at Cambridge.—On Dec. 24th I went to Playford."



CHAPTER VII.

AT GREENWICH OBSERVATORY—1856 TO 1866.

1856

"In the Report to the Visitors there is an interesting account of the difficulties experienced with the Reflex Zenith Tube in consequence of the tremors of the quicksilver transmitted through the ground. Attempts were made to reduce the tremor by supporting the quicksilver trough on a stage founded at a depth of 10 feet below the surface, but it was not in the smallest degree diminished, and the Report states that 'The experience of this investigation justifies me in believing that no practicable depth of trench prevents the propagation of tremor when the soil is like that of Greenwich Hill, a gravel, in all places very hard, and in some, cemented to the consistency of rock.'—With respect to the regulation of the Post Office clocks, 'One of the galvanic clocks in the Post Office Department, Lombard Street, is already placed in connection with the Royal Observatory, and is regulated at noon every day ... other clocks at the General Post Office are nearly prepared for the same regulation, and I expect that the complete system will soon be in action.'—Under the head of General Remarks a careful summary is given of the work of the Observatory, and the paragraph concludes as follows: 'Lastly there are employments which connect the scientific Observatory with the practical world; the distribution of accurate time, the improvement of marine time-keepers, the observations and communications which tend to the advantage of Geography and Navigation, and the study, in a practical sense, of the modifications of Magnetism; a careful attention to these is likely to prove useful to the world, and conducive to the material prosperity of the Observatory: and these ought not to be banished from our system.'—In September I prepared the first specification for the building to carry the S.E. Dome.—In September, learning that Hansen's Lunar Tables were finished in manuscript, I applied to Lord Clarendon and they were conveyed to me through the Foreign Office: in October I submitted to the Admiralty the proposal for printing the Tables, and in November I learned that the Treasury had assented to the expense.—Lieut. Daynou's eclipses and occultations for longitudes of points in South Africa, observed in 1854 and 1855, were calculated here in this year.—On Feb. 16th I made my first application to Sir C. Wood (First Lord of the Admiralty) for assistance to C. Piazzi Smyth to carry out the Teneriffe Experiment: grounding it in part on the failure of attempts to see the solar prominences. He gave encouragement, and on Mar. 18th I transmitted Piazzi Smyth's Memorial to the Admiralty: on May 2nd the Admiralty authorized an expense of L500. I drew up suggestions.—The Sheepshanks Fund: After the death of my friend Richard Sheepshanks, his sister Miss Anne Sheepshanks wished to bestow some funds in connection with the University of Cambridge, Trinity College, and Astronomy, to which his name should be attached. There must have been some conversation with me, but the first letter is one from De Morgan in August. In September I had a conversation with Miss Sheepshanks, and sent her my first draft of a scheme, to which she assented. On Sept. 30th I wrote to Whewell (Master of Trinity) who was much trusted by Miss Sheepshanks: he consented to take part, and made some suggestions. There was further correspondence, but the business did not get into shape in this year.—In connection with the Correction of the Compass in Iron Ships: I discussed the observations made in the voyage of the Royal Charter. On Feb. 13th I proposed to the Admiralty a system of mounting the compasses with adjustable magnets, and it was ordered to be tried in the Trident and Transit.—In February I reported to the Admiralty that the Deal Time-Ball had been successful, and I proposed time-balls at Portsmouth, Plymouth, and Sheerness. There was much correspondence in various directions about Portsmouth and Devonport, and in March I went to Devonport and specially examined Mount Wise and the Devonport Column.—I had correspondence with Sir Howard Douglas about the sea breaking over the unfinished Dover Pier. I have an idea that this followed evidence given by me to a Harbour Commission, in which I expressed as a certainty that the sea will not be made to break by a vertical wall."

Of private history: "I returned from Playford on Jan. 18th.—From June 16th to August 5th I was, with my son Wilfrid, on an expedition to South Italy and Sicily: on our return from Sicily, we remained for three days ill at Marseilles from a touch of malaria.—On Dec. 22nd I went to Playford.—In acknowledgment of the pleasure which I had derived from excursions in the Cumberland Passes, I made a foot-bridge over a troublesome stream on the Pass of the Sty Head."

1857

"In the Report to the Visitors, when on the subject of the Altazimuth, the following paragraph occurs: 'I alluded in a preceding section to the cutting away of a very small portion of one of the rays of the three-armed pier which carries the Altazimuth. The quality of the brickwork is the best that I have ever seen, and not a single brick was disturbed beyond those actually removed. Yet the effect was to give the Altazimuth an inclination of about 23". This inclination evidently depends on the elasticity of the brickwork.'—With reference to the new S.E. Equatoreal the Report states that 'The support of the north or upper end of the polar axis has been received, and is planted within the walls of the building in a position convenient for raising it to its ultimate destination. It is one piece of cast-iron, and weighs nearly 5 tons.'—Small changes as previously mentioned had been noticed with regard to the Zero of Azimuth of the Transit Circle, and the Report states that 'In regard to the Azimuth of the Transit Circle, and the Azimuth of its Collimator, Mr Main has brought together the results of several years, and the following law appears to hold. There is a well-marked annual periodical change in the position of the Transit Circle, the southerly movement of the eastern pivot having its minimum value in September, and its maximum in March, the extreme range being about 14 seconds; and there is a similar change, but of smaller amount, in the position of the Collimator. I cannot conjecture any cause for these changes, except in the motion of the ground. There is also a well-marked connection between the state of level of the axis and the temperature. The eastern pivot always rises when the temperature rises, the extreme range being about 6 seconds. I cannot offer any explanation of this.'—Under the head of Extraneous Works the Report states that 'The British Government had for some years past contributed by pecuniary grants to the preparation of Prof. Hansen's Lunar Tables. In the last winter they undertook the entire expense of printing a large impression of the Tables. The reading of the proof-sheets (a very considerable labour) has been effected entirely at the Observatory. I may take this opportunity of stating that the use of these Tables has enabled me, as I think, incontestably to fix the capture of Larissa to the date B.C. 557, May 19. This identification promises to prove valuable, not merely for its chronological utility, but also for its accurate determination of an astronomical epoch, the point eclipsed being exactly known, and the shadow having been very small.'—In April I gave a lecture to the Royal Astronomical Society on the methods available through the next 25 years for the determination of the Sun's parallax.—Dr Livingstone's observations for African longitudes were computed at the Observatory.—The Admiralty enquire of me about the feasibility of adopting Piazzi Smyth's construction for steadying telescopes on board ship: I gave a Report, of mixed character, on the whole discouraging.—I had correspondence with G.P. Bond and others about photographing the Stars and Moon.—On Feb. 17th Piazzi Smyth's books, &c. relating to the Teneriffe Experiment were sent to me: I recommended that an abridged Report should be sent to the Royal Society.—Respecting the Sheepshanks Fund: there was correspondence with Miss Sheepshanks and Whewell, but nothing got into shape this year: Miss Sheepshanks transferred to me L10,000 lying at Overend and Gurney's.—In November experiments were made for the longitude of Edinburgh, which failed totally from the bad state of the telegraph wire between Deptford and the Admiralty.—In June the first suggestion was made to me by Capt. Washington for time-signals on the Lizard Point: which in no long time I changed for the Start Point.—The Admiralty call for estimates for a time-ball at Portsmouth: on receiving them they decline further proceeding.—I was engaged in speculations and correspondence about the Atlantic Submarine Cable.—In the Royal Astronomical Society, I presented Memoirs and gave lectures on the three great chronological eclipses (Agathocles, Thales, Larissa)."—On Dec. 5th Airy wrote to the Vice-Chancellor of the University of Cambridge, objecting to the proposed changes regarding the Smith's Prizes—a subject in which he took much interest, and to which he ascribed great importance.—On Apr. 27th I was in correspondence with G. Herbert of the Trinity House, about floating beacons.—In July I reported to the Treasury on the Swedish Calculating Engine (I think on the occasion of Mr Farr, of the Registrar-General's Office, applying for one).—In November I had correspondence about the launch of the Great Eastern, and the main drainage of London."

Of private history: "On Jan. 14th I returned from Playford.—From June 27th to Aug. 5th I was travelling in Scotland with my wife and two eldest sons, chiefly in the West Highlands. On our return we visited Mrs Smith (my wife's mother) at Brampton.—On Dec. 26th I went to Playford."

1858

"In the Minutes of the Visitors it is noted that the new Queen's Warrant was received. The principal change was the exclusion of the Astronomer Royal and the other Observatory Officers from the Board.—In the Report to the Visitors it is stated that 'The Papers of the Board of Longitude are now finally stitched into books. They will probably form one of the most curious collections of the results of scientific enterprise, both normal and abnormal, which exists.'—It appears that the galvanic communications, external to the Observatory, had been in a bad state, the four wires to London Bridge having probably been injured by a thunderstorm in the last autumn, and the Report states that 'The state of the wires has not enabled us to drop the Ball at Deal. The feeble current which arrives there has been used for some months merely as giving a signal, by which an attendant is guided in dropping the Ball by hand.'—Regarding the new Equatoreal the Report states that 'For the new South-East Equatoreal, the object-glass was furnished by Messrs Merz and Son in the summer of last year, and I made various trials of it in a temporary tube carried by the temporary mounting which I had provided, and finally I was well satisfied with it. I cannot yet say that I have certainly divided the small star of gamma Andromedae; but, for such a test, a combination of favourable circumstances is required. From what I have seen, I have no doubt of its proving a first-rate object-glass.'—On March 15th was an annular eclipse of the Sun, for the observation of which I sent parties fully equipped to Bedford, Wellingborough, and Market Harborough. The observations failed totally in consequence of the bad weather: I myself went to Harrowden near Wellingborough.—Respecting the Altazimuth, the Report states that with due caution as to the zero of azimuth 'the results of observation are extremely good, very nearly equal to those of the meridional instrument; perhaps I might say that three observations with the Altazimuth are equivalent to two with the Transit Circle.'—Respecting Meteorological Observations the Report states that 'The observations of the maximum and minimum thermometers in the Thames, interrupted at the date of the last Report, have been resumed, and are most regularly maintained. Regarding the Thames as the grand climatic agent on London and its neighbourhood, I should much regret the suppression of these observations.'—After much trouble the longitude of Edinburgh had been determined: 'the retard of the current is 0.04s very nearly, and the difference of longitudes 12m 43.05s, subject to personal equations.'—The Report concludes thus: 'With regard to the direction of our labours, I trust that I shall always be supported by the Visitors in my desire to maintain the fundamental and meridional system of the Observatory absolutely intact. This, however, does not impede the extension of our system in any way whatever, provided that such means are arranged for carrying out the extension as will render unnecessary the withdrawal of strength from what are now the engrossing objects of the Observatory.'—I had much correspondence on Comets, of which Donati's great Comet was one: the tail of this Comet passed over Arcturus on October 5th.—Respecting the Sheepshanks Fund: In September I met Whewell at Leeds, and we settled orally the final plan of the scheme. On Oct. 27th I saw Messrs Sharp, Miss Sheepshanks's solicitors, and drew up a Draft of the Deed of Gift. There was much correspondence, and on Nov. 20th I wrote to the Vice-Chancellor of Cambridge University. A counter-scheme was proposed by Dr Philpott, Master of St Catharine's College. By arrangement I attended the Council of the University on Dec. 3rd, and explained my views, to which the Council assented. On Dec. 9th the Senate accepted the gift of Miss Sheepshanks.—I had much correspondence throughout this year, with the Treasury, Herschel, Sabine, and the Royal Society, about the continuation of the Magnetic Establishments. The Reductions of the Magnetic Observations 1848-1857 were commenced in February of this year, under the direction of Mr Lucas, a computer who had been engaged on the Lunar Reductions.—In this year I came to a final agreement with the South Eastern Railway Company about defining the terms of our connection with them for the passage of Time Signals. I was authorized by the Admiralty to sign the 'protocol' or Memorandum of Agreement, and it was signed by the South Eastern Railway Directors.—On Aug. 28th I made my first proposal to Sir John Packington (First Lord of the Admiralty) for hourly time signals on the Start Point, and in September I went to the Start to examine localities, &c. On Dec. 23rd the Admiralty declined to sanction it.—I presented to the Royal Society a Paper about drawing a great-circle trace on a Mercator's chart.—In October I gave a Lecture on Astronomy in the Assembly Room at Bury.—On Jan. 25th I was busied with my Mathematical Tracts for republication."—In this year Airy published in the Athenaeum very careful and critical remarks on the Commissioners' Draft of Statutes for Trinity College. He was always ready to take action in the interests of his old College. This Paper procured him the warmest gratitude from the Fellows of the College.

Of private history: "On Jan. 23rd I returned from Playford. From July 5th to Aug. 6th I was on an expedition in Switzerland with my two eldest sons. At Paris we visited Le Verrier, and at Geneva we visited Gautier, De La Rive, and Plantamour. We returned by Brussels.—On Dec. 23rd I went to Playford."—In this year was erected in Playford Churchyard a granite obelisk in memory of Thomas Clarkson. It was built by subscription amongst a few friends of Clarkson's, and the negociations and arrangements were chiefly carried out by Airy, who zealously exerted himself in the work which was intended to honour the memory of his early friend. It gave him much trouble during the years 1856 to 1858.

Here is a letter to the Editor of the Athenaeum on some other Trinity matters:

1858, November 22.

DEAR SIR,

In the Athenaeum of November 20, page 650, column 3, paragraph 4, there is an account of the erection of the statue of Barrow in Trinity College Antechapel (Cambridge) conceived in a spirit hostile to the University, and written in great ignorance of the facts. On the latter I can give the writer some information.

The Marquis of Lansdowne, who was a Trinity man and whose son was of Trinity, intimated to the authorities of the College that he was desirous of placing in the antechapel a statue of Milton. This, regard being had to the customs and the college-feelings of Cambridge, was totally impossible. The antechapel of every college is sacredly reserved for memorials of the men of that college only; and Milton was of Christ's College. The Marquis of Lansdowne, on hearing this objection, left the choice of the person to be commemorated, to certain persons of the college, one of whom (a literary character of the highest eminence and a profound admirer of Milton) has not resided in Cambridge for many years. Several names were carefully considered, and particularly one (not mentioned by your correspondent) of very great literary celebrity, but in whose writings there is ingrained so much of ribaldry and licentiousness that he was at length given up. Finally the choice rested on Barrow, not as comparable to Milton, but as a person of reputation in his day and as the best who could be found under all the circumstances.

Cromwell never was mentioned; he was a member of Sidney College: moreover it would have been very wrong to select the exponent of an extreme political party. But Cromwell has I believe many admirers in Cambridge, to which list I attach myself.

I had no part in the negociations above mentioned, but I saw the original letters, and I answer for the perfect correctness of what I have stated. But as I am not a principal, I decline to appear in public.

It is much to be desired, both for the Athenaeum and for the public, that such an erroneous statement should not remain uncorrected. And I would suggest that a correction by the Editor would be just and graceful, and would tend to support the Athenaeum in that high position which it has usually maintained.

I am, dear Sir, Yours very faithfully, G.B. AIRY.

Hepworth Dixon, Esq.

1859

"The Report to the Visitors states that 'The Lunar Reductions with amended elements (especially parallax) for correction of Observations from 1831 to 1851 are now completed. It is, I think, matter of congratulation to the Observatory and to Astronomy, that there are now exhibited the results of uninterrupted Lunar Observations extending through more than a century, made at the same place, reduced under the same superintendence and on the same general principles, and compared throughout with the same theoretical Tables.'—After reference to the great value of the Greenwich Lunar Observations to Prof. Hansen in constructing his Tables, and to the liberality of the British Government in their grants to Hansen, the Report continues thus: 'A strict comparison of Hansen's Tables with the Greenwich Observations of late years, both meridional and extra-meridional, was commenced. The same observations had, in the daily routine of the Observatory, been compared with the Nautical Almanac or Burckhardt's Tables. The result for one year only (1852) has yet reached me, but it is most remarkable. The sum of squares of residual errors with Hansen's Tables is only one-eighth part of that with Burckhardt's Tables. When it is remembered that in this is included the entire effect of errors and irregularities of observation, we shall be justified in considering Hansen's Tables as nearly perfect. So great a step, to the best of my knowledge, has never been made in numerical physical theory. I have cited this at length, not only as interesting to the Visitors from the circumstance that we have on our side contributed to this great advance, but also because an innovation, peculiar to this Observatory, has in no small degree aided in giving a decisive character to the comparison. I have never concealed my opinion that the introduction and vigorous use of the Altazimuth for observations of the Moon is the most important addition to the system of the Observatory that has been made for many years. The largest errors of Burckhardt's Tables were put in evidence almost always by the Altazimuth Observations, in portions of the Moon's Orbit which could not be touched by the meridional instruments; they amounted sometimes to nearly 40" of arc, and they naturally became the crucial errors for distinction between Burckhardt's and Hansen's Tables. Those errors are in all cases corrected with great accuracy by Hansen's Tables.'—The Report concludes with the following paragraph: 'With the inauguration of the new Equatoreal will terminate the entire change from the old state of the Observatory. There is not now a single person employed or instrument used in the Observatory which was there in Mr Pond's time, nor a single room in the Observatory which is used as it was used then. In every step of change, however, except this last, the ancient and traditional responsibilities of the Observatory have been most carefully considered: and, in the last, the substitution of a new instrument was so absolutely necessary, and the importance of tolerating no instrument except of a high class was so obvious, that no other course was open to us. I can only trust that, while the use of the Equatoreal within legitimate limits may enlarge the utility and the reputation of the Observatory, it may never be permitted to interfere with that which has always been the staple and standard work here.'—Concerning the Sheepshanks Fund: There was much correspondence about settling the Gift till about Feb. 21st. I took part in the first examination for the Scholarship in October of this year, and took my place with the Trinity Seniority, as one of their number on this foundation, for some general business of the Fund.—With respect to the Correction of the Compass in Iron Ships: I sent Mr Ellis to Liverpool to see some practice there in the correction of the Compass. In September I urged Mr Rundell to make a voyage in the Great Eastern (just floated) for examination of her compasses, and lent him instruments: very valuable results were obtained. Mr Archibald Smith had edited Scoresby's Voyage in the Royal Charter, with an introduction very offensive to me: I replied fully in the Athenaeum of Nov. 7th.—The Sale of Gas Act: An Act of Parliament promoted by private members of the House of Commons had been passed, without the knowledge or recollection of the Government. It imposed on the Government various duties about the preparation of Standards. Suddenly, at the very expiration of the time allowed this came to the knowledge of Government. On Oct. 1st Lord Monteagle applied to me for assistance. On Oct. 15th and 22nd I wrote to Mr Hamilton, Secretary of the Treasury, and received authority to ask for the assistance of Prof. W.H. Miller.—I made an examination of Mr Ball's eyes (long-sighted and short-sighted I think).—In February I made an Analysis of the Cambridge Tripos Examination, which I communicated to some Cambridge residents." In a letter on this subject to one of his Cambridge friends Airy gives his opinion as follows: "I have looked very carefully over the Examination Papers, and think them on the whole very bad. They are utterly perverted by the insane love of Problems, and by the foolish importance given to wholly useless parts of Algebraical Geometry. For the sake of these, every Physical Subject and every useful application of pure mathematics are cut down or not mentioned." This led to much discussion at Cambridge. In this year the Smith's Prizes were awarded to the 4th and 6th Wranglers.

Of private history: "On Apr. 29th Mrs Smith (my wife's mother) died at Brampton.—From July 4th to Aug. 2nd I was in France (Auvergne and the Vivarais) with my two eldest sons. Maclear travelled with us to Paris.—On Dec. 23rd I went to Playford."—Antiquities and historical questions connected with military movements had a very great attraction for Airy. On his return from the expedition in France above-mentioned, he engaged in considerable correspondence with military authorities regarding points connected with the battle of Toulouse. And in this year also he had much correspondence with the Duke of Northumberland concerning his Map of the Roman Wall, and the military points relating to the same.

1860

"In June Mr Main accepted the office of Radcliffe Observer at Oxford (Mr Johnson having died) and resigned the First Assistancy at Greenwich: in October Mr Stone was appointed First Assistant.—At an adjourned Meeting of the Visitors on June 18th there were very heavy discussions on Hansen's merits, and about the grant to him. Papers were read from Sir J. Lubbock, Babbage, South, Whewell, and me. Finally it was recommended to the Government to grant L1000 to Hansen, which was paid to him.—In the Report to the Board of Visitors the following remark occurs: 'The apparent existence of a discordance between the results of Direct Observations and Reflection Observations (after the application of corrections for flexure, founded upon observations of the horizontal collimator wires) to an extent far greater than can be explained by any disturbance of the direction of gravity on the quicksilver by its distance from the vertical, or by the attraction of neighbouring masses, perplexes me much.'—With respect to the discordance of dips of the dipping-needles, which for years past had been a source of great trouble and puzzle, the Report states that 'The dipping-needles are still a source of anxiety. The form which their anomalies appear to take is that of a special or peculiar value of the dip given by each separate needle. With one of the 9-inch needles, the result always differs about a quarter of a degree from that of the others. I can see nothing in its mechanical construction to explain this.—Reference is made to the spontaneous currents through the wires of telegraph companies, which are frequently violent and always occur at the times of magnetic storms, and the Report continues 'It may be worth considering whether it would ever be desirable to establish in two directions at right angles to each other (for instance, along the Brighton Railway and along the North Kent Railway) wires which would photographically register in the Royal Observatory the currents that pass in these directions, exhibiting their indications by photographic curves in close juxtaposition with the registers of the magnetic elements.'—In connection with the Reduction of the Greenwich Lunar Observations from 1831 to 1851, the Report states that 'The comparison of Hansen's Lunar Tables with the Greenwich Observations, which at the last Visitation had been completed for one year only, has now been finished for the twelve years 1847 to 1858. The results for the whole period agree entirely, in their general spirit, with those for the year 1852 cited in the last Report. The greatest difference between the merits of Burckhardt's and Hansen's Tables appears in the Meridional Longitudes 1855, when the proportion of the sum of squares of errors is as 31 (Burckhardt) to 2 (Hansen). The nearest approach is in the Altazimuth Latitudes 1854, when the proportion of the sum of squares of errors is as 12 (Burckhardt) to 5 (Hansen).'—A special Address to the Members of the Board of Visitors has reference to the proposals of M. Struve for (amongst other matters) the improved determination of the longitude of Valencia, and the galvanic determination of the extreme Eastern Station of the British triangles.—On Sept. 13th I circulated amongst the Visitors my Remarks on a Paper entitled 'On the Polar Distances of the Greenwich Transit-Circle, by A. Marth,' printed in the Astronomische Nachrichten; the Paper by Mr Marth was an elaborate attack on the Greenwich methods of observation, and my Remarks were a detailed refutation of his statements.—On Oct. 20th I made enquiry of Sabine as to the advantage of keeping up magnetic observations. On Oct. 22nd he wrote, avoiding my question in some measure, but saying that our instruments must be changed for such as those at Kew (his observatory): I replied, generally declining to act on that advice.—In March and April I was in correspondence with Mr Cowper (First Commissioner of Works, &c.) about the bells of the Westminster Clock; also about the smoky chimneys of the various apartments of the Palace. On Apr. 21st I made my Report on the clock and bells, 20 foolscap pages. I employed a professional musician to examine the tones of the bells.—In November I was writing my book on Probable Errors, &c.—I was engaged on the Tides of Kurrachee and Bombay.—The first examination of Navy telescopes was made for the Admiralty. —Hoch's Paper on Aberration appeared in the Astronomische Nachrichten. This (with others) led to the construction of the water-telescope several years later.—In September I wrote in the Athenaeum against a notion of Sir H. James on the effect of an upheaval of a mountain in changing the Earth's axis. In October I had drawn up a list of days for a possible evagation of the Earth's poles: but apparently nothing was done upon them.

"In this year I was a good deal occupied for the Lighthouse Commission. On Feb. 21st Admiral Hamilton (chairman) applied to me for assistance. In April I went to Chance's Factory in Birmingham on this business. In May I made my report on the Start Lighthouse, after inspection with the Commission. In June, with my son Hubert, I visited the Whitby Lighthouses, and discovered a fault of a singular kind which most materially diminished their power. This discovery led to a general examination of lighthouses by the Trinity Board, to a modification of many, and to a general improvement of system. On June 25th I reported on the Lights at Calais, Cap de Valde, Grisnez, South Foreland, and North Foreland. In August I had been to the North Foreland again, and in September to Calais and the Cap d'Ailly. In October I went with my son Hubert to Aberdeen to see the Girdleness Lighthouse. On Nov. 10th I made a General Report.

"This was the year of the great total solar eclipse visible in Spain. At my representation, the Admiralty placed at my command the large steamship 'Himalaya' to carry about 60 astronomers, British and Foreign. Some were landed at Santander: I with many at Bilbao. The Eclipse was fairly well observed: I personally did not do my part well. The most important were Mr De La Rue's photographic operations. At Greenwich I had arranged a very careful series of observations with the Great Equatoreal, which were fully carried out."

The eclipse expedition to Spain, shortly referred to above, was most interesting, not merely from the importance of the results obtained (and some of the parties were very fortunate in the weather) but from the character of the expedition. It was a wonderful combination of the astronomers of Europe, who were all received on board the 'Himalaya,' and were conveyed together to the coast of Spain. The polyglot of languages was most remarkable, but the utmost harmony and enthusiasm prevailed from first to last, and this had much to do with the general success of the expedition. Those who landed at Bilbao were received in the kindest and most hospitable manner by Mr C.B. Vignoles, the engineer-in-chief of the Bilbao and Tudela Railway, which was then under construction. This gentleman made arrangements for the conveyance of parties to points in the interior of the country which were judged suitable for the observation of the eclipse, and placed all the resources of his staff at the disposal of the expedition in the most liberal manner. The universal opinion was that very great difficulty would have been experienced without the active and generous assistance of Mr Vignoles. It is needless to say that the vote of thanks to Mr Vignoles, proposed by the Astronomer Royal during the return voyage, was passed by acclamation and with a very sincere feeling of gratitude: it was to the effect that 'without the great and liberal aid of Mr C.B. Vignoles, and the disinterested love of science evinced by him on this occasion, the success of the "Himalaya" eclipse expedition could not have been ensured.' There is a graphic and interesting account of the reception of the party at Bilbao given in the 'Life of C.B. Vignoles, F.R.S., Soldier and Civil Engineer,' by O.J. Vignoles, M.A.

Of private history: "On May 26th my venerable friend Arthur Biddell died. He had been in many respects more than a father to me: I cannot express how much I owed to him, especially in my youth.—From June 12th to 15th I visited the Whitby Lighthouses with my son Hubert.—From July 6th to 28th I was in Spain, on the 'Himalaya' expedition, to observe the total eclipse: I was accompanied by my wife, my eldest son, and my eldest daughter.—From Oct. 5th to 18th I went with my son Hubert to Aberdeen to see the Girdleness Lighthouse, making lateral trips to Cumberland in going and returning.—On Dec. 21st I went to Playford."

1861

"In the Report to the Visitors there is great complaint of want of room. 'With increase of computations, we want more room for computers; with our greatly increased business of Chronometers and Time-Distribution, we are in want of a nearly separate series of rooms for the Time-Department: we want rooms for book-stores; and we require rooms for the photographic operations and the computations of the Magnetic Department.'—The Report gives a curious history of Dr Bradley's Observations, which in 1776 had been transferred to the University of Oxford, and proceeds thus: 'More lately, I applied (in the first instance through Lord Wrottesley) to the Vice-Chancellor, Dr Jeune, in reference to the possibility of transferring these manuscripts to the Royal Observatory.... Finally, a decree for the transfer of the manuscript observations to the Royal Observatory, without any condition, was proposed to Convocation on May 2nd, and was passed unanimously. And on May 7th my Assistant, Mr Dunkin, was sent to Oxford to receive them. And thus, after a delay of very nearly a century, the great work of justice is at length completed, and the great gap in our manuscript observations is at length filled up.'—With reference to the Transit Circle, it had been remarked that the Collimators were slightly disturbed by the proximity of the gas-flames of their illuminators, and after various experiments as to the cause of it, the Report proceeds thus: 'To my great surprise, I found that the disturbance was entirely due to the radiation of the flame upon a very small corner (about 16 square inches) of the large and massive stone on which the collimator is planted. The tin plates were subsequently shaped in such a manner as to protect the stone as well as the metal; and the disturbance has entirely ceased.' —Regarding the large S.E. Equatoreal, the Report states that 'On the character of its object-glass I am now able to speak, first, from the examination of Mr Otto Struve, made in a favourable state of atmosphere; secondly, from the examinations of my Assistants (I have not myself obtained a sight of a test-object on a night of very good definition). It appears to be of the highest order. The small star of gamma Andromedae is so far separated as to shew a broad dark space between its components. Some blue colour is shewn about the bright planets.'—It is noted in the Report that 'The Equatoreal observations of the Solar Eclipse are completely reduced; and the results are valuable. It appears from them that the error in right ascension of Burckhardt's Lunar Tables at the time of the eclipse amounted to about 38"; while that of Hansen's (ultimately adopted by Mr Hind for the calculation of the eclipse) did not exceed 3".'—With regard to Chronometers it is stated that 'By use of the Chronometer Oven, to which I have formerly alluded, we have been able to give great attention to the compensation. I have reason to think that we are producing a most beneficial effect on the manufacture and adjustment of chronometers in general.'—With regard to the Cape of Good Hope Observatory and Survey, the Admiralty enquire of me when the Survey work will be completed, and I enquire of Maclear 'How is the printing of your Survey Work?' In 1862 I began to press it strongly, and in 1863 very strongly.—I introduced a method (constantly pursued since that time at the Royal Observatory) for computing interpolations without changes of sign.—I had correspondence with Herschel and Faraday, on the possible effect of the Sun's radiant heat on the sea, as explaining the curve of diurnal magnetic inequality. (That diurnal inequality was inferred from the magnetic reductions 1848-1857, which were terminated in 1860.)—Regarding the proposal of hourly time-signals on the Start Point, I consulted telegraph engineers upon the practical points, and on Dec. 21st I proposed a formal scheme, in complete detail. (The matter has been repeatedly brought before the Admiralty, but has been uniformly rejected.)—I was engaged on the question of the bad ocular vision of two or three persons.—The British Association Meeting was held at Manchester: I was President of Section A. I gave a Lecture on the Eclipse of 1860 to an enormous attendance in the Free Trade Hall." The following record of the Lecture is extracted from Dr E.J. Routh's Obituary Notice of Airy written for the Proceedings of the Royal Society. "At the meeting of the British Association at Manchester in 1861, Mr Airy delivered a Lecture on the Solar Eclipse of 1860 to an assembly of perhaps 3000 persons. The writer remembers the great Free Trade Hall crowded to excess with an immense audience whose attention and interest, notwithstanding a weak voice, he was able to retain to the very end of the lecture....The charm of Professor Airy's lectures lay in the clearness of his explanations. The subjects also of his lectures were generally those to which his attention had been turned by other causes, so that he had much that was new to tell. His manner was slightly hesitating, and he used frequent repetitions, which perhaps were necessary from the newness of the ideas. As the lecturer proceeded, his hearers forgot these imperfections and found their whole attention rivetted to the subject matter."

Of private history: "On Jan. 2nd there was a most remarkable crystallization of the ice on the flooded meadows at Playford: the frost was very severe.—From June 20th to Aug. 1st I was at the Grange near Keswick (where I hired a house) with my wife and most of my family.—From Nov. 5th to 14th I was on an expedition in the South of Scotland with my son Wilfrid: we walked with our knapsacks by the Roman Road across the Cheviots to Jedburgh.—On Dec. 21st I went to Playford."

1862

"The Report to the Board of Visitors states that 'A new range of wooden buildings (the Magnetic Offices) is in progress at the S.S.E. extremity of the Magnetic Ground. It will include seven rooms.'—Also 'I took this opportunity (the relaying of the water-main) of establishing two powerful fire-plugs (one in the Front Court, and one in the Magnetic Ground); a stock of fire-hose adapted to the "Brigade-Screw" having been previously secured in the Observatory.'—'Two wires, intended for the examination of spontaneous earth-currents, have been carried from the Magnetic Observatory to the Railway Station in the town of Greenwich. From this point one wire is to be led to a point in the neighbourhood of Croydon, the other to a point in the neighbourhood of Dartford. Each wire is to be connected at its two extremities with the Earth. The angle included between the general directions of these two lines is nearly a right angle.'—'The Kew unifilar magnetometer, adapted to the determination of the horizontal part of terrestrial magnetic force in absolute measure, was mounted in the summer of 1861; and till 1862 February, occasional observations (14 in all) were taken simultaneously with the old and with the new instrument. The comparison of results shewed a steady but very small difference, not greater probably than may correspond to the omission of the inverse seventh powers of distance in the theoretical investigation; proving that the old instrument had been quite efficient for its purpose.'—Great efforts had been made to deduce a law from the Diurnal Inequalities in Declination and Horizontal Force, as shewn by the Magnetic observations; but without success: the Report states that 'The results are most amazing, for the variation in magnitude as well as in law. What cosmical change can be indicated by them is entirely beyond my power of conjecture.'—'I have alluded, in the two last Reports, to the steps necessary, on the English side, for completing the great Arc of Parallel from Valencia to the Volga. The Russian portion of the work is far advanced, and will be finished (it is understood) in the coming summer. It appeared to me therefore that the repetition of the measure of astronomical longitude between Greenwich and Valencia could be no longer delayed. Two Assistants of the Royal Observatory (Mr Dunkin and Mr Criswick) will at once proceed to Valencia, for the determination of local time and the management of galvanic signals.'—'I now ask leave to press the subject of Hourly Time Signals at the Start Point on the attention of the Board, and to submit the advantage of their addressing the Board of Admiralty upon it. The great majority of outward-bound ships pass within sight of the Start, and, if an hourly signal were exhibited, would have the means of regulating their chronometers at a most critical part of their voyage. The plan of the entire system of operations is completely arranged. The estimated expense of outfit is L2017, and the estimated annual expense is L326; both liable to some uncertainty, but sufficiently exact to shew that the outlay is inconsiderable in comparison with the advantages which might be expected from it. I know no direction of the powers of the Observatory which would tend so energetically to carry out the great object of its establishment, viz. "the finding out the so much desired Longitude at Sea."'—The attention of the Visitors is strongly drawn to the pressure on the strength of the Observatory caused by the observation of the numerous small planets, and the paragraph concludes thus: 'I shall, however, again endeavour to effect a partition of this labour with some other Observatory.'—A small fire having occurred in the Magnetic Observatory, a new building of zinc, for the operation of naphthalizing the illuminating gas, is in preparation, external to the Observatory: and thus one of the possible sources of accidental fire will be removed.—Miss Sheepshanks added, through me, L2000 to her former gift: I transferred it, I believe, to the Master and Seniors of Trinity College."—In this year Airy contributed to the Royal Society two Papers, one "On the Magnetic properties of Hot-Rolled and Cold-Rolled Malleable Iron," the other "On the Strains in the Interior of Beams." He gave evidence before the Select Committee on Weights and Measures, and also before the Public Schools Commission.

In the latter part of 1862 a difference arose between Airy and Major-General Sabine, in consequence of remarks made by the latter at a meeting of the Committee of Recommendations of the British Association. These remarks were to the effect "That it is necessary to maintain the complete system of self-registration of magnetic phenomena at the Kew Observatory, because no sufficient system of magnetic record is maintained elsewhere in England"; implying pointedly that the system at the Royal Observatory of Greenwich was insufficient. This matter was taken up very warmly by Airy, and after a short and acrimonious correspondence with Sabine, he issued a private Address to the Visitors, enclosing copies of the correspondence with his remarks, and requesting the Board to take the matter of this attack into their careful consideration. This Address is dated November 1862, and it was followed by another dated January 1863, which contains a careful reply to the various points of General Sabine's attack, and concludes with a distinct statement that he (the Astronomer Royal) can no longer act in confidence with Sabine as a Member of the Board of Visitors.

Of private history: There were the usual short visits to Playford at the beginning and end of the year.—From June 28th to Aug. 5th he was in Scotland (chiefly in the Western Highlands) with his wife and his sons Hubert and Osmund. In the course of this journey he visited the Corryvreckan whirlpool near the island of Scarba, and the following paragraph relating to this expedition is extracted from his journal: "Landed in Black Mile Bay, island of Luing, at 10.30. Here by previous arrangement with Mr A. Brown, agent of the steam-boat company, a 4-oared boat was waiting to take us to Scarba and the Corryvreckan. We were pulled across to the island of Lunga, and rowed along its length, till we came to the first channel opening from the main sea, which the sailors called the Little Gulf. Here the sea was rushing inwards in a manner of which I had no conception. Streams were running with raving speed, sometimes in opposite directions side by side, with high broken-headed billows. Where the streams touched were sometimes great whirls (one not many yards from our boat) that looked as if they would suck anything down. Sometimes among all this were great smooth parts of the sea, still in a whirling trouble, which were surrounded by the mad currents. We seemed entirely powerless among all these."

In the beginning of this year (1862) the Duke of Manchester, in writing to the Rev. W. Airy, had said, "I wish your brother, the Astronomer Royal, could be induced to have investigations made as to whether the aspects of the Planets have any effect on the weather." This enquiry produced the following reply:

A subject like that of the occult influences of the planets (using the word occult in no bad sense but simply as meaning not thoroughly traced) can be approached in two ways—either by the a priori probability of the existence of such influences, or by the a posteriori evidence of their effects. If the two can be combined, the subject may be considered as claiming the dignity of a science. Even if the effects alone are certain, it may be considered that we have a science of inferior degree, wanting however that definiteness of law and that general plausibility which can only be given when true causes, in accordance with antecedent experience in other cases, can be suggested.

Now in regard to the a priori probability of the existence of planetary influences, I am far from saying that such a thing is impossible. The discoveries of modern philosophy have all tended to shew that there may be many things about us, unknown even to the scientific world, but which well-followed accidents reveal with the most positive certainty. It is known that every beam of light is accompanied by a beam of chemical agency, totally undiscoverable to the senses of light or warmth, but admitting of separation from the luminous and warm rays; and producing photogenic effects. We know that there are disturbances of magnetism going on about us, affecting whole continents at a time, unknown to men in general, but traceable with facility and certainty, and which doubtless affect even our brains and nerves (which are indisputably subject to the influence of magnetism).

Now in the face of these things I will not undertake to say that there is any impossibility, or even any want of plausibility in the supposition that bodies external to the earth may affect us. It may well be cited in its favour that it is certain that the sun affects our magnetism (it is doubtful whether it does so immediately, or mediately by giving different degrees of warmth to different parts of the earth), and it is believed on inferior evidence that the moon also affects it. It may therefore seem not impossible or unplausible that other celestial bodies may affect perhaps others of the powers of nature about us. But there I must stop. The denial of the impossibility is no assertion of the truth or probability, and I absolutely decline to take either side—either that the influences are real, or that the influences are unreal—till I see evidence of their effects.

Such evidence it is extremely difficult to extract from ordinary facts of observation. I have alluded to the sun's daily disturbance of the magnet as one of the most certain of influences, yet if you were to observe the magnet for a single day or perhaps for several days, you might see no evidence of that influence, so completely is it involved with other disturbances whose causes and laws are totally unknown.

I believe that, in addition to the effects ascribable to Newtonian gravitation (as general motion of the earth, precession of the equinoxes, and tides), this magnetic disturbance is the only one yet established as depending on an external body. Men in general, however, do not think so. It appears to be a law of the human mind, to love to trace an effect to a cause, and to be ready to assent to any specious cause. Thus all practical men of the lower classes, even those whose pecuniary interests are concerned in it, believe firmly in the influence of the moon upon the winds and the weather. I believe that every careful examiner of recorded facts (among whom I place myself as regards the winds) has come to the conclusion that the influence of the moon is not discoverable.

I point out these two things (magnetic disturbances and weather) as tending to shew that notoriety or the assumed consent of practical men, are of no value. The unnotorious matter may be quite certain, the notorious matter may have no foundation. Everything must stand on its own evidence, as completely digested and examined.

Of such evidence the planetary influence has not a particle.

My intended short note has, in the course of writing, grown up into a discourse of very unreasonable length; and it is possible that a large portion of it has only increased obscurity. At any rate I can add nothing, I believe, which can help to explain more fully my views on this matter.

* * * * *

In this year (1862, June 9th) Airy received the Honorary Degree of LL.D. in the University of Cambridge. He was nominated by the Duke of Devonshire, as appears from the following letter:

LISMORE CASTLE, IRELAND, April 19th, 1862.

MY DEAR SIR,

It is proposed according to usage to confer a considerable number of Honorary Degrees on the occasion of my first visit to Cambridge as Chancellor of the University.

I hope that you will allow me to include your name in that portion of the list which I have been invited to draw up.

The ceremony is fixed for the 10th of June.

I am, my dear Sir, Yours very truly, DEVONSHIRE.

The Astronomer Royal.

* * * * *

Airy's reply was as follows:

ROYAL OBSERVATORY, GREENWICH, LONDON, S.E. 1862, April 21.

MY LORD DUKE,

I am exceedingly gratified by your communication this day received, conveying a proposal which I doubt not is suggested by your Grace's recollection of transactions now many years past.

I have always been desirous of maintaining my connection with my University, and have in various ways interested myself practically in its concerns. It would give me great pleasure to have the connection strengthened in the flattering way which you propose.

I had conceived that alumni of the University were not admissible to honorary degrees; but upon this point the information possessed by your Grace, as Chancellor of the University, cannot be disputed.

I am, my Lord Duke, Your Grace's very faithful servant, G.B. AIRY.

His Grace The Duke of Devonshire.

* * * * *

There were in all 19 Honorary Degrees of Doctor of Laws conferred on the 9th of June, including men of such eminence as Armstrong, Faraday, and Fairbairn.

1863

In this year there were several schemes for a Railway through the lower part of Greenwich Park, the most important being the scheme of the London, Chatham and Dover Railway Company. In reference to this scheme the Report to the Visitors states "I may say briefly that I believe that it would be possible to render such a railway innocuous to the Observatory; it would however be under restrictions which might be felt annoying to the authorities of the Railway, but whose relaxation would almost ensure ruin to the Observatory."—"The meridional observations of Mars in the Autumn of 1862 have been compared with those made at the Observatory of Williamstown, near Melbourne, Australia, and they give for mean solar parallax the value 8.932", exceeding the received value by about 1/24th part. (A value nearly identical with this 8.93" has also been found by comparing the Pulkowa and Cape of Good Hope Observations.)"—"The results of the new Dip-Instrument in 1861 and 1862 appear to give a firm foundation for speculations on the state and change of the dip. As a general result, I may state as probable that the value of dip in the middle of 1843 was about 69 deg.1', and in the middle of 1862 about 68 deg.11'. The decrease of dip appears to be more rapid in the second half of this interval than in the first; the dip at beginning of 1853 being about 68 deg.44'."—With reference to the re-determination of the longitude of Valencia, it is stated that "The concluded longitude agrees almost exactly with that determined by the transmission of chronometers in 1844; and entitles us to believe that the longitudes of Kingstown and Liverpool, steps in the chronometer conveyance, were determined with equal accuracy."—"The computations, for inferring the direction and amount of movement of the Solar System in space from the observed proper motions of 1167 stars, have been completed. The result is, that the Sun is moving towards a point, R.A. 264 deg., N.P.D. 65 deg. (not very different from Sir W. Herschel's, but depending much in N.P.D. on the accuracy of Bradley's quadrant observations), and that its annual motion subtends, at the distance of a star of the first magnitude, the angle 0.4". But the comparison, of the sum of squares of apparent proper motions uncorrected, with the sum of squares of apparent proper motions corrected for motion of Sun, shews so small an advance in the explanation of the star's apparent movements as to throw great doubt on the certainty of results; the sum of squares being diminished by only 1/25th part."—"I had been writing strongly to Maclear on the delays in publishing both the geodetic work and the Star Catalogue at the Cape of Good Hope: he resolves to go on with these works. In December I am still very urgent about the geodesy."

Of private history: There was the usual short visit to Playford at the beginning and end of the year.—"From June 27th to August 10th I was travelling in the North and West of Scotland with my wife, my youngest son Osmund, and my daughter Annot."

* * * * *

In this year the offer of Knighthood (for the third time) was made to Airy through the Rt Hon. Sir George C. Lewis, Bart. The offer was accepted on Feb. 12th, 1863, but on the same day a second letter was written as follows:

1863, Feb. 12.

DEAR SIR,

I am extremely ignorant of all matters connected with court ceremonial, and in reference to the proposed Knighthood would ask you:—

1. I trust that there is no expense of fees. To persons like myself of small fortune an honour may sometimes be somewhat dear.

2. My highest social rank is that given by my Academical Degree of D.C.L. which I hold in the Universities of Oxford and Cambridge. In regard to costume, would it be proper that I should appear in the scarlet gown of that degree? or in the ordinary Court Dress?

I am, Dear Sir, Yours very faithfully, G.B. AIRY.

The Right Honourable Sir George C. Lewis, Bart., &c. &c. &c.

To this letter Sir G.C. Lewis replied that the fees would amount to about L30, an intimation which produced the following letter:

ROYAL OBSERVATORY, GREENWICH, S.E. 1863, Feb. 19th.

DEAR SIR,

I have to acknowledge your letter of yesterday: and I advert to that part of it in which it is stated that the Fees on Knighthood amount to about L30.

Twenty-seven years ago the same rank was offered to me by Lord John Russell and Mr Spring Rice (then Ministers of the Crown), with the express notice that no fees would be payable. I suppose that the usage (whatever it be) on which that notice was founded still subsists.

To a person whose annual income little more than suffices to meet the annual expenses of a very moderate establishment, an unsought honour may be an incumbrance. It appears, at any rate, opposed to the spirit of such an honour, that it should be loaded with Court Expenses in its very creation.

I hope that the principle stated in 1835 may serve as precedent on this occasion.

I am, dear Sir, Your very faithful servant, G.B. AIRY.

The Right Honourable Sir G. C. Lewis, Bart., &c. &c. &c.

No intimation however was received that the fees would be remitted on the present occasion, and after consideration the proposed Knighthood was declined in the following letter:

ROYAL OBSERVATORY, GREENWICH, S.E. 1863, April 15.

DEAR SIR,

I have frequently reflected on the proposal made by you of the honour of Knighthood to myself. I am very grateful to you for the favourable opinion which you entertain in regard to my supposed claims to notice, and for the kindness with which you proposed publicly to express it. But on consideration I am strongly impressed with the feeling that the conditions attached by established regulation to the conferring of such an honour would be unacceptable to me, and that the honour itself would in reality, under the circumstances of my family-establishment and in my social position, be an incumbrance to me. And finally I have thought it best most respectfully, and with a full sense of the kindness of yourself and of the Queen's Government towards me, to ask that the proposal might be deferred.

There is another direction in which a step might be made, affecting my personal position in a smaller degree, but not tending to incommode me, which I would ask leave to submit to your consideration. It is, the definition of the Rank of the Astronomer Royal. The singular character of the office removes it from ordinary rules of rank, and sometimes may produce a disagreeable contest of opinions. The only offices of similar character corresponding in other conditions to that of the British Astronomer Royal are those of the Imperial Astronomers at Pulkowa (St Petersburg) and Paris. In Russia, where every rank is clearly defined by that of military grade, the Imperial Astronomer has the rank of Major-General. In France, the definition is less precise, but the present Imperial Astronomer has been created (as an attachment of rank to the office) a Senator of the Empire.

I am, dear Sir, Your very faithful servant, G.B. AIRY.

The Rt Hon. Sir George C. Lewis, Bart., &c. &c. &c.

Sir G. C. Lewis died before receiving this letter, and the letter was afterwards forwarded to Lord Palmerston. Some correspondence followed between Lord Palmerston and Airy on the subject of attaching a definite rank to the office of Astronomer Royal, as proposed in the above letter. But the Home Office (for various reasons set forth) stated that the suggestion could not be complied with, and the whole subject dropped.

1864

The following remarks are extracted from the Report of the Astronomer Royal to the Board of Visitors.—"In a very heavy squall which occurred in the gale of December 2 of last year, the stay of the lofty iron pillar outside of the Park Rails, which carried our telegraph wires, gave way, and the pillar and the whole system of wires fell."—"An important alteration has been made in the Magnetic Observatory. For several years past, various plans have been under consideration for preventing large changes of temperature in the room which contains the magnetic instruments. At length I determined to excavate a subterraneous room or cellar under the original room. The work was begun in the last week in January, and in all important points it is now finished."—"In the late spring, some alarm was occasioned by the discovery that the Parliamentary Standard of the Pound Weight had become coated with an extraneous substance produced by the decomposition of the lining of the case in which it was preserved. It was decided immediately to compare it with the three Parliamentary Copies, of which that at the Observatory is one. The National Standard was found to be entirely uninjured."—"On November 16 of last year, the Transit Instrument narrowly escaped serious injury from an accident. The plate chain which carries the large western counterpoise broke. The counterpoise fell upon the pier, destroying the massive gun-metal wheels of the lifting machinery, but was prevented from falling further by the iron stay of the gas-burner flue."—"The Prismatic Spectrum-Apparatus had been completed in 1863. Achromatic object-glasses are placed on both sides of the prism, so that each pencil of light through the prism consists of parallel rays; and breadth is given to the spectrum by a cylindrical lens. The spectral lines are seen straighter than before, and generally it is believed that their definition is improved."—"For observation of the small planets, a convention has been made with M. Le Verrier. From new moon to full moon, all the small planets visible to 13h are observed at the Royal Observatory of Greenwich. From full moon to new moon, all are observed at the Imperial Observatory of Paris. The relief gained in this way is very considerable."—"In determining the variations in the power of the horizontal-force and vertical-force magnets depending on temperature, it was found by experiment that this depended materially on whether the magnet was heated by air or by water, and 'The result of these experiments (with air) is to give a coefficient for temperature correction four or five times as great as that given by the water-heatings,'"—"With regard to the discordances of the results of observations of dip-needles, experiments had been made with needles whose breadth was in the plane passing through the axis of rotation, and it appeared that the means of extreme discordances were, for an ordinary needle 11' 45", and for a flat needle 3' 27"," and the Report continues thus: "After this I need not say that I consider it certain that the small probable errors which have been attributed to ordinary needles are a pure delusion."—The Report states that in the various operations connected with the trials and repairs of chronometers, and the system of time-signals transmitted to various time-balls and clocks, about one-fourth of the strength of the Observatory is employed, and it continues thus: "Viewing the close dependence of Nautical Astronomy upon accurate knowledge of time, there is perhaps no department of the Observatory which answers more completely to the original utilitarian intentions of the Founder of the Royal Observatory."—"With regard to the proposal of time-signals at the Start Point, it appears that communications referring to this proposal had passed between the Board of Admiralty and the Board of Trade, of which the conclusion was, that the Board of Trade possessed no funds applicable to the defraying of the expenses attending the execution of the scheme. And the Admiralty did not at present contemplate the establishment of these time-signals under their own authority."—Amongst other Papers in this year, Airy's Paper entitled "First Analysis of 177 Magnetic Storms," &c., was read before the Royal Society.

Of private history: "There was the usual visit to Playford in the beginning of the year.—From June 8th to 23rd I made an excursion with my son Hubert to the Isle of Man, and the Lake District.—From Sept. 7th to 14th I was on a trip to Cornwall with my two eldest sons, chiefly in the mining district.—In August of this year my eldest (surviving) daughter, Hilda, was married to Mr E.J. Routh, Fellow of St Peter's College, Cambridge, at Greenwich Parish Church. They afterwards resided at Cambridge."

1865

"Our telegraphic communications of every kind were again destroyed by a snow-storm and gale of wind which occurred on Jan. 28th, and which broke down nearly all the posts between the Royal Observatory and the Greenwich Railway Station.—The Report to the Visitors states that 'The only change of Buildings which I contemplate as at present required is the erection of a fire-proof Chronometer Room. The pecuniary value of Chronometers stored in the Observatory is sometimes perhaps as much as L8000.'—The South Eastern and London Chatham and Dover scheme for a railway through the Park was again brought forward. There was a meeting of Sir J. Hanmer's Committee at the Observatory on May 26th. Mr Stone was sent hastily to Dublin to make observations on Earth-disturbance by railways there. I had been before the Committee on May 25th. On Sept. 1st I approved of an amended plan. In reference to this matter the Report states that 'It is proper to remark that the shake of the Altazimuth felt in the earthquake of 1863, Oct. 5th, when no such shake was felt with instruments nearer to the ground (an experience which, as I have heard on private authority, is supported by observation of artificial tremors), gives reason to fear that, at distances from a railway which would sufficiently defend the lower instruments, the loftier instruments (as the Altazimuth and the Equatoreals) would be sensibly affected.'—Some of the Magnets had been suspended by steel wires, instead of silk, of no greater strength than was necessary for safety, and the Report states that 'Under the pressure of business, the determination of various constants of adjustment was deferred to the end of the year. The immediate results of observation, however, began to excite suspicion; and after a time it was found that, in spite of the length of the suspending wire (about 8 feet) the torsion-coefficient was not much less than 1/6. The wires were promptly dismounted, and silk skeins substituted for them. With these, the torsion-coefficient is about 1/210.'—The Dip-Instrument, which had given great trouble by the irregularities of the dip-results, had been compared with two dip-instruments from Kew Observatory, which gave very good and accordant results. 'It happened that Mr Simms, by whom our instruments now in use were prepared, and who had personally witnessed our former difficulties, was present during some of these experiments. Our own instrument being placed in his hands (Nov. 10th to 19th) for another purpose, he spontaneously re-polished the apparently faultless agate-bearings. To my great astonishment, the inconsistencies of every kind have nearly or entirely vanished. On raising and lowering the needles, they return to the same readings, and the dips with the same needle appear generally consistent.' Some practical details of the polishing process by which this result had been secured are then given.—After numerous delays, the apparatus for the self-registration of Spontaneous Earth Currents was brought into a working state in the month of March. A description of the arrangement adopted is given in the Report.—'All Chronometers on trial are rated every day, by comparison with one of the clocks sympathetic with the Motor Clock. Every Chronometer, whether on trial or returned from a chronometer-maker as repaired, is tried at least once in the heat of the Chronometer-Oven, the temperature being usually limited to 90 deg. Fahrenheit; and, guided by the results of very long experience, we have established it as a rule, that every trial in heat be continued through three weeks.'—'The only employment extraneous to the Observatory which has occupied any of my time within the last year is the giving three Lectures on the Magnetism of Iron Ships (at the request of the Lords of the Committee of Council on Education) in the Theatre of the South Kensington Museum. The preparations, however, for these Lectures, to be given in a room ill-adapted to them, occupied a great deal of my own time, and of the time of an Assistant of the Observatory.'—'Referring to a matter in which the interests of Astronomy are deeply concerned, I think it right to report to the Visitors my late representation to the Government, to the effect that, in reference to possible observation of the Transit of Venus in 1882, it will be necessary in no long time to examine the coasts of the Great Southern Continent.'"

Of private history: "There were the usual visits to Playford at the beginning and end of the year.—From June 18th to 26th I was on a trip in Wales with my sons Hubert and Osmund.—From Sept. 6th to Oct. 2nd I was staying with most of my family at Portinscale near Keswick: we returned by Barnard Castle, Rokeby, &c."



CHAPTER VIII.

AT GREENWICH OBSERVATORY—1866 TO 1876.

1866

In this year the cube of the Transit Circle was pierced, to permit reciprocal observations of the Collimators without raising the instrument. This involved the construction of improved Collimators, which formed the subject of a special Address to the Members of the Board of Visitors on Oct. 21st 1865.—From the Report to the Visitors it appears that "On May 23rd 1865, a thunderstorm of great violence passed very close to the Observatory. After one flash of lightning, I was convinced that the principal building was struck. Several galvanometers in the Magnetic Basement were destroyed. Lately it has been remarked that one of the old chimneys of the principal building had been dislocated and slightly twisted, at a place where it was surrounded by an iron stay-band led from the Telegraph Pole which was planted upon the leads of the Octagon Room."—"On consideration of the serious interruptions to which we have several times been exposed from the destruction of our open-air Park-wires (through snow-storms and gales), I have made an arrangement for leading the whole of our wires in underground pipes as far as the Greenwich Railway Station."—"The Committee of the House of Commons, to whom the Greenwich and Woolwich Line of the South Eastern Railway was referred, finally assented to the adoption of a line which I indicated, passing between the buildings of the Hospital Schools and the public road to Woolwich."—"The Galvanic Chronometer attached to the S. E. Equatoreal often gave us a great deal of trouble. At last I determined, on the proposal of Mr Ellis, to attempt an extension of Mr R. L. Jones's regulating principle. It is well known that Mr Jones has with great success introduced the system of applying galvanic currents originating in the vibrations of a normal pendulum, not to drive the wheelwork of other clocks, but to regulate to exact agreement the rates of their pendulums which were, independently, nearly in agreement; each clock being driven by weight-power as before. The same principle is now applied to the chronometer.... The construction is perfectly successful; the chronometer remains in coincidence with the Transit Clock through any length of time, with a small constant error as is required by mechanical theory."—"The printed volume of Observations for 1864 has two Appendixes; one containing the calculations of the value of the Moon's Semi-diameter deduced from 295 Occultations observed at Cambridge and Greenwich from 1832 to 1860, and shewing that the Occultation Semi-diameter is less than the Telescopic Semi-diameter by 2"; the other containing the reduction of the Planetary Observations made at the Royal Observatory in the years 1831-1835; filling up the gap, between the Planetary Reductions 1750-1830 made several years ago under my superintendence, and the Reductions contained in the Greenwich Volumes 1836 to the present time: and conducted on the same general principles."—"Some trouble had been found in regulating the temperature of the Magnetic Basement, but it was anticipated that in future there would be no difficulty in keeping down the annual variation within about 5 deg. and the diurnal variation within 3 deg..—Longitudes in America were determined in this year by way of Valencia and Newfoundland: finished by Nov. 14th."

Of private history: In April he made a short visit to Ventnor in the Isle of Wight.—From June 15th to July 23rd he was on an expedition in Norway with his son Osmund and his nephew Gorell Barnes.—There was probably a short stay at Playford in the winter.

In this and in the previous year (1865) the free-thinking investigations of Colenso, the Bishop of Natal, had attracted much notice, and had procured him the virulent hostility of a numerous section. His income was withheld from him, and in consequence a subscription fund was raised for his support by his admirers. Airy, who always took the liberal side in such questions, was a subscriber to the fund, and wrote the following letter to the Bishop:

ROYAL OBSERVATORY, GREENWICH, S.E., 1865, July 24.

MY LORD,

With many thanks I have to acknowledge your kind recollection of me in sending as a presentation copy the work on Joshua, Judges, and especially on the divided authorship of Genesis; a work whose investigations, founded in great measure on severe and extensive verbal criticism, will apparently bear comparison with your Lordship's most remarkable examination of Deuteronomy. I should however not do justice to my own appreciation if I did not remark that there are other points considered which have long been matters of interest to me.

On several matters, some of them important, my present conclusions do not absolutely agree with your Lordship's. But I am not the less grateful for the amount of erudition and thought carefully directed to definite points, and above all for the noble example of unwearied research and freedom in stating its consequences, in reference to subjects which scarcely ever occupy the attention of the clergy in our country.

I am, My Lord, Yours very faithfully, G.B. AIRY.

The Lord Bishop of Natal.

* * * * *

Here also is a letter on the same subject, written to Professor Selwyn, Professor of Divinity at Cambridge:—

ROYAL OBSERVATORY, GREENWICH, LONDON, S.E., 1866, May 5.

MY DEAR SIR,

The MS. concerning Colenso duly arrived.

I note your remarks on the merits of Colenso. I do not write to tell you that I differ from you, but to tell you why I differ.

I think that you do not make the proper distinction between a person who invents or introduces a tool, and the person who uses it.

The most resolute antigravitationist that ever lived might yet acknowledge his debt to Newton for the Method of Prime and Ultimate Ratios and the Principles of Fluxions by which Newton sought to establish gravitation.

So let it be with Colenso. He has given me a power of tracing out truth to a certain extent which I never could have obtained without him. And for this I am very grateful.

As to the further employment of this power, you know that he and I use it to totally different purposes. But not the less do I say that I owe to him a new intellectual power.

I quite agree with you, that the sudden disruption of the old traditional view seems to have unhinged his mind, and to have sent him too far on the other side. I would not give a pin for his judgment.

Nevertheless, I wish he would go over the three remaining books of the Tetrateuch.

I know something of Myers, but I should not have thought him likely to produce anything sound on such things as the Hebrew Scriptures. I never saw his "Thoughts."

I am, my dear Sir, Yours very truly, G.B. AIRY.

Professor Selwyn.

* * * * *

The following letter has reference to Airy's proposal to introduce certain Physico-Mathematical subjects into the Senate-House Examination for B.A. Honors at Cambridge. On various occasions he sharply criticized the Papers set for the Senate-House Examination and the Smith's Prize Examination, and greatly lamented the growing importance of pure mathematics and the comparative exclusion of physical questions in those examinations. His proposal as finally submitted in the letter that follows was somewhat modified (as regards the mode of introducing the subjects) from his original draft, in deference to the opinions of Whewell, Adams, Routh, and other friends to whom he had submitted it. His proposal was favourably received by the Mathematical Board, and recommendations were made in the direction, though not to the extent, that he desired, and he subsequently submitted a Memorandum on those recommendations:

ROYAL OBSERVATORY, GREENWICH, 1866, May 11.

MY DEAR SIR,

You will perceive, from perusal of the enclosed paper, that I have acted on the permission which you kindly gave me, to transmit to you my proposal for extension of the mathematical education of the University in the Physical direction.

It is an unavoidable consequence of the structure of the University that studies there will have a tendency to take an unpractical form depending much on the personal tastes of special examiners. I trust that, as a person whose long separation from the daily business of the University has enabled him to see in some measure the wants of the external scientific and practical world, I may be forgiven this attempt to bring to the notice of the University my ideas on the points towards which their attention might perhaps be advantageously turned.

I am, my dear Sir, Very faithfully yours, G.B. AIRY.

The Rev. Dr Cartmell, Master of Christ's College and Vice-Chancellor.

ROYAL OBSERVATORY, GREENWICH, 1866, May 11.

MY DEAR MR VICE-CHANCELLOR,

About two years ago, by the kindness of the University, an opportunity was presented to me of orally stating what I conceived to be deficiencies in the educational course of the University as regards mathematical physics. Since that time, the consideration of those deficiencies, which had long been present to me, has urged itself on my attention with greater force: and finally I have entertained the idea that I might without impropriety communicate to you my opinion, in a less fugitive form than on the occasion to which I have alluded: with the request that, if you should deem such a course appropriate, you would bring it before the Board of Mathematical Studies, and perhaps ultimately make it known to the Resident Members of the Senate.

I will first give the list of subjects, which I should wish to see introduced, and to the prosecution of which the generally admirable course of the University is remarkably well adapted: and I will then, without entering into every detail, advert to the process by which I think it probable the introduction of these subjects could be effected.

In the following list, the first head is purely algebraical, and the second nearly so: but they are closely related to observational science, and to the physical subjects which follow. Some of the subjects which I exhibit on my list are partially, but in my opinion imperfectly, taught at present. I entirely omit from my list Physical Optics, Geometrical Astronomy, and Gravitational Astronomy of Points: because, to the extent to which Academical Education ought to go, I believe that there is no teaching on these sciences comparable to that in the University of Cambridge. (It is, of course, still possible that improvements may be made in the books commonly used.) It might, however, be a question, whether, as regards the time and manner of teaching them, some parts of these subjects might ultimately be associated with the other subjects included in my list.

I. List of subjects proposed for consideration.

(1) Partial Differential Equations to the second order, with their arbitrary functions: selected principally with reference to the physical subjects.

(2) The Theory of Probabilities as applied to the combination of Observations.

(3) Mechanics (including Hydraulic Powers) in the state which verges upon practical application, and especially including that part in which the abstract ideas of power and duty occur.

(4) Attractions. This subject is recognized in the existing course of the University: but, so far as I can infer from examination-papers, it appears to be very lightly passed over.

(5) The Figure of the Earth, and its consequences, Precession, &c. I believe that the proposal is sanctioned, of adopting some part of this theory in the ordinary course; but perhaps hardly so far as is desirable.

(6) The Tides.

(7) Waves of Water.

(8) Sound (beginning with Newton's investigation); Echoes; Pipes and Vibrating Strings; Acoustics; the Mathematical part of Music.

(9) Magnetism, terrestrial and experimental, and their connection.

(I omit for the present Mineralogy and Mathematical Electricity.)

This list of subjects appears formidable: but they are in reality easy, and would be mastered in a short time by the higher Wranglers.

II. Mode of introducing these subjects into the University.

After much consideration, and after learning the opinions of several persons whose judgment claims my deepest respect, I propose the gradual introduction of these subjects into the Examination for Honors at admission to the B.A. Degree, as soon as the preparation of Books and the readiness of Examiners shall enable the University to take that step. I conceive that, by a judicious pruning of the somewhat luxuriant growth of Pure Algebra, Analytical Geometry, and Mere Problems, sufficient leisure may be gained for the studies of the undergraduates, and sufficient time for the questions of the examiners. I do not contemplate that the students could advance very far into the subjects; but I know the importance of beginning them; and, judging from the train of thoughts, of reading, and of conversation, among the Bachelors with whom I associated many years ago, I believe that there is quite a sufficient number who will be anxious to go deep into the subjects if they have once entered into them. If six Wranglers annually would take them up, my point would be gained. The part which these gentlemen might be expected, in a short time, to take in the government of the University, would enable them soon to act steadily upon the University course: the efficiency of the University instruction would be increased; and the external character of the University would be raised.

The real difficulties, and they are not light ones, would probably be found in providing Examiners and Books. At present, both are wanting within the University. Where there is a great and well-founded objection to intrusting examinations to persons foreign to the University, and where the books have to be created with labour and with absolute outlay of money (for their sale could never be remunerative), the progress must be slow. Still progress would be certain, if the authorities of the University should think the matter deserving of their hearty encouragement.

Requesting that you and the Members of the University will accept this proposal as an indication of my deep attachment to my University,

I am, My dear Mr Vice-Chancellor, Your very faithful servant, G.B. AIRY.

The Rev. Dr Cartmell, &c. &c. Vice-Chancellor of the University of Cambridge.

1867

"In this year it was arranged that my Treasury accounts were to be transferred to the Admiralty, making the simplification which I had so long desired.—From the Report to the Visitors it appears that a relic of the Geodetic operations commenced in 1787 for connecting the Observatories of Greenwich and Paris, in the shape of an observing cabin on the roof of the Octagon Room, was shifted and supported in such a manner that the pressure on the flat roof was entirely avoided.—With regard to the Transit Circle, the new Collimators with telescopes of seven inches aperture had been mounted. When the Transit Telescope directed vertically is interposed, the interruptions in the central cube impair the sharpness of definition, still leaving it abundantly good for general use. It had been regarded as probable that the astronomical flexure of the telescope, after cutting away small portions of the central cube, would be found sensibly changed: and this proved to be the case. The difference of flexures of the two ends has been altered more than a second of arc.—Referring to a new Portable Altazimuth which had lately been tested, the Report states as follows: 'I may mention that a study of defects in the vertical circle of a small Altazimuth formerly used by me, and an inspection of the operations in the instrument-maker's work-shop, have convinced me that the principal error to be feared in instruments of this class is ovality of the graduated limb; this cannot be eliminated by two microscopes, and such an instrument should never be fitted with two only. Our instrument has four.'—'In Osler's Anemometer, a surface of 2 square feet is now exposed to the wind instead of one foot as formerly; and the plate is supported by weak vertical springs instead of rods running on rollers. Its indications are much more delicate than formerly.'—'The Meteors on Nov. 14th were well observed. Eight thousand and three hundred were registered. The variations of frequency at different times were very well noted. The points of divergence were carefully determined.'—Referring to the gradual improvement in the steadiness of chronometers from 1851 to 1866, it appears that from 1851 to 1854 the 'trial number' (which is a combination of changes of weekly rate representing the fault of the chronometer) varied from 34.8s to 52.5s, while from 1862 to 1866 it varied from 21.2s to 25.8s.—The following statement will shew the usual steadiness of the Great Clock on the Westminster Palace: On 38 per cent. of days of observation, the clock's error was below 1s. On 38 per cent, the error was between 1s and 2s. On 21 per cent. it was between 2s and 3s. On 2 per cent. between 3s and 4s. On 1 per cent. between 4s and 5s.—The Report contains an account of the determination of the longitude of Cambridge U.S. by Dr B. A. Gould, by means of galvanic currents through the Atlantic Cable, in the spring of 1867: and advantage was taken of this opportunity for re-determining the longitude of Feagh Main near Valencia in Ireland. The longitude of Feagh Main, found by different methods is as follows: By chronometers in 1844, 41m 23.23s; by galvanic communication with Knight's Town in 1862, 41m 23.37s; by galvanic communication with Foilhommerum in 1866, 41m 23.19s. The collected results for longitude of Cambridge U.S. from different sources are: By moon-culminators (Walker in 1851, and Newcomb in 1862-3), 4h 44m 28.42s and 4h 44m 29.56s respectively; by Eclipses (Walker in 1851), 4h 44m 29.64s; by occultations of Pleiades (Peirce 1838-1842, and 1856-1861), 4h 44m 29.91s and 4h 44m 30.90s respectively; by chronometers (W. C. Bond in 1851, and G. P. Bond in 1855), 4h 44m 30.66s and 4h 44m 31.89s respectively; by Atlantic Cable 1866, 4h 44m 30.99s.—After noticing that many meteorological observatories had suddenly sprung up and had commenced printing their observations in detail, the Report continues thus: 'Whether the effect of this movement will be that millions of useless observations will be added to the millions that already exist, or whether something may be expected to result which will lead to a meteorological theory, I cannot hazard a conjecture. This only I believe, that it will be useless, at present, to attempt a process of mechanical theory; and that all that can be done must be, to connect phenomena by laws of induction. But the induction must be carried out by numerous and troublesome trials in different directions, the greater part of which would probably be failures.'—There was this year an annular eclipse; I made large preparations at the limits of the annularity; failed entirely from very bad weather."—In this year Airy contributed a Paper to the Institution of Civil Engineers 'On the use of the Suspension Bridge with stiffened roadway for Railway and other Bridges of Great Span,' for which a Telford Medal was awarded to him by the Council of the Institution. And he communicated several Papers to the Royal Society and the Royal Astronomical Society.