The other Proposition was made to Charles Magna, Anno 793. for joyning the Euxine Sea and the Ocean together, by a Channel, which was begun for that end, and designed to be 2000. paces long and 100. paces broad, betwixt the River Altmull, falling into the Danube above Ratisbone, and the River Rott, passing at Nurenberg, and thence running into the Main, and so into the Rhine. But yet this also proved abortive, though there was great appearance of success at first.

* * * * *

Of the Way of killing Ratle-Snakes.

There being not long since occasion given at a meeting of the Royal Society to discourse of Ratle Snakes, that worthy and inquisitive Gentleman, Captain Silas Taylor, related the manner, how they were killed in Virginia, which he afterwards was pleased to give in writing, attested by two credible persons in whose presence it was done; which is, as follows.

The Wild Penny-royal or Ditany of Virginia, groweth streight up about one foot high, with the leaves like Penny-royal, with little blue tufts at the joyning of the branches to the Plant, the colour of the Leaves being a reddish green, but the Water distilled, of the colour of Brandy, of a fair Yellow: the Leaves of it bruised are very hot biting upon the Tongue: and of these, so bruised, they took some, and having tyed them in the cleft of a long stick, they held them to the Nose of the Ratle-Snake, who by turning and wriggling laboured as much as she could to avoid it: but she was killed with it, in less than half an hours time, and, as was supposed, by the scent thereof; which was done Anno 1657. in the Month of July, at which season, they repute those creatures to be in the greatest vigour for their poison. {44}

* * * * *

A Relation of Persons killed with subterraneous Damps.

This Relation was likewise made to the Royal Society, by that Eminent Virtuoso Sir R. Moray, who was pleased, upon their desire, to give it them in writing; as followeth.

In a Coal-pit, belonging to the Lord Sinclair in Scotland, where the Coal is some 18 or 20 foot thick, and antiently wasted to a great depth: The Colliers, some Weeks agoe, having wrought as deep as they could, and being to remove into new Rooms (as they call them) did, by taking off, as they retired, part of the Coal that was left as Pillars to support the Roof and Earth over it, so much weaken them, that within a short space, after they were gone out of the Pitt, the Pillars falling, the Earth above them filled up the whole Space, where the Colliers had lately wrought, with its ruins. The Colliers being here-by out of work, some of them adventured to work upon old remains of Walls, so near the old wastes, that striking through the slender partition of the Coal-wall, that seperated between them and the place, where they used to work, they quickly perceived their Errour, and fearing to be stifled by the bad Air, that they knew, possessed these old wastes, in regard not onely of the Damps, which such wastes do usually afford, but because there having for many years been a Fire in those wastes, that filled them with stifling fumes and vapors, retired immediately and saved themselves from the eruptions of the Damp. But next day some seven or eight of them came no sooner so farr down the staires, that led them to the place where they had been the day before, as they intended, but upon their stepping into the place, where the Air was infected, they fell down dead, as if they had been shott: And there being amongst them one, whose Wife was informed he was stifled in that place, she went down so far without inconvenience, that seeing her Husband near her, ventured to go to him, but being choaked by the Damp, as soon as she came near him, she fell down dead by him. {45}

This Story of Sir R. Moray affirmed to have received from the Earl of Weymes, Brother in Law to the Lord Sinclair, as it was written to him from Scotland.

* * * * *

Of the Mineral of Liege, yeilding both Brimstone and Vitriol, and the way of extracting them out of it, used at Liege.

The Account of this Mineral, and of the way of extracting both Brimstone and Vitriol out of it, was procured from Liege, by the lately mentioned Sir Robert Moray and by him communicated to the Royal Society, as follows.

The Mineral, out of which Brimstone and Vitriol are extracted, is one and the same, not much unlike Lead ore, having also oft times much Lead mingled with it, which is seperated from it by picking it out of the rest. The Mines resemble our English Coal Mines dugg according to the depth of the Mineral, 15, 20, or more fathoms, as the Vein leads the Workmen, or the subterranean waters will give them leave, which in Summer so overflow the Mines, that the upper waters, by reason of the drought, not sufficing to make the Pumps goe, the Work ceases.

To make Brimstone, they break the Stone or Ore into small pieces, which they put into Crucibles made of Earth, five foot long, square and Pyramid-wise. The Entry is near a foot square. These Crucibles are laid sloaping, eight undermost, and seven above them, as it were betwixt them, that the Fire may come at them all, each having its particular Furnace or Oven. The Brimstone being dissolved by the violence of the heat, drops out at the small end of the Crucible, and falls into a Leaden-Trough or Receptacle, common to all the said Crucibles, through which there runs a continual Rivolet of cold water, conveyed thither by Pipes for the cooling of the dissolved Sulphur, which is ordinarily four hours in melting. This done, the Ashes are drawn out by a crooked Iron, and being put into an Iron Wheel barrow, are carried out of the Hutt, and {46} being laid in a heap, are covered with other exiled or drained Ashes, the better to keep them warm; which is reiterated, as long as they make Brimstone.

To make Coperas or Vitriol, they take a quantity of the said Ashes, and throwing them into a square planked pit in the Earth, some four foot deep, and eight foot square, they cover the same with ordinary water, and let it lye twenty four hours, or until an Egg will swim upon the liquor, which is a sign, that it is strong enough. When they will boyl this, they let it run through Pipes into the Kettles, adding to it half as much Mother-water, which is that water, that remains after boyling of the hardned Coperas. The Kettles are made of Lead, 41/2 foot high, 6 foot long, and 3 foot broad, standing upon thick Iron Barrs or Grates. In these the Liquor is boyled with a strong Coal-fire, twenty four hours or more, according to the strength or weakness of the Lee or Water. When it is come to a just consistence, the fire is taken away, and the boyled liquor suffered to cool somewhat, and then it is tapp'd out of the said Kettles, through holes beneath in the sides of them, and conveyed through wooden Conduits into several Receptacles, three foot deep and four foot long (made and ranged not unlike our Tan-pits) where it remains fourteen or fifteen dayes, or so long till the Coperas separate it self from the water, and becomes icy and hard. The remaining water is the above-mentioned Mother-water; and the elixed or drained Ashes are the Dregs, or Caput mortuum, which the Lee, whereof the Vitriol is made, leaves behind it in the planked Pits.

* * * * *

A further Account of Mr. Boyle's Experimental History of Cold.

In the first Papers of these Philosophical Transactions, some promise was made of a fuller account, to be given by the next, of the Experimental History of Cold, composed by the Honourable Mr. Robert Boyle; it being then supposed, that this History would have been altogether printed off at the time of publishing the {47} Second Papers of these Transactions; but the Press, employed upon this Treatise, having been retarded somewhat longer than was ghessed, the said promise could not be performed before this time: wherein it now concerns the inquiring World to take notice, that this subject, as it hath hitherto bin almost totally neglected, so it is now, by this Excellent Author, in such a manner handled, and improved by near Two hundred choice Experiments and Observations, that certainly the Curious and Intelligent Reader will in the perusal thereof find cause to admire both the Fertility of a Subject, seemingly so barren, and the Author's Abilities of improving the same to so high a Degree.

But to take a short view of some of the particulars of this History, and thereby to give occasion to Philosophical men, to take this Subject more into their consideration, than hitherto hath been done; the Ingenious Readers will here see,

1, That not only all sorts of Acid and Alcalizate Salts, and Spirits, even Spirit of Wine, but also Sugar, and Sugar of Lead mixed with Snow, are capable of freezing other Bodies, and upon what account they are so.

2, That among the Substances capable of being frozen, there are not only all gross sorts of Saline Bodies, but such also as are freed from their grosser parts, not excepting Spirit of Urine, the Lixivium of Pot-ashes, nor Oyl of Tartar, per deliquium, it self.

3, That many very spiritous liquors, freed from their aqueous parts, cannot be brought to freeze, neither naturally, nor artificially: And here is occasionally mentioned a way of keeping Moats unpassable in very cold Countries, recorded by Olaus Magnus.

4, What are the ways proper to estimate the greater or lesser Coldness of Bodies; and by what means we can measure the intensness of Cold produced by Art, beyond that, which Nature needs to employ for the freezing of Water; as also, in what proportion water of a moderate degree of Coldness will {48} be made to shrink by Snow and Salt, before it begin by Congelation to expand it self; and then, how to measure by the differing Weight and Density of the same portion of Water, what change was produced in it, betwixt the hottest time of Summer, and first glaciating degree of Cold, and then the highest, which our Author could produce by Art: Where an Inquiry is annex'd, whether the making of these kind of Tryals with the waters of the particular Rivers and Seas, men are to sail on, may afford any useful estimate, whether or not, and how much, ships may on those waters be safely loaden more in Winter, than in Summer. To which is added the way of making exact Discoveries of the differing degrees of Coldness in differing Regions, by such Thermometers, as are not subject to the alterations of the Atmosphere's gravitation, nor to be frozen.

5. Whether, in Cold, the diffusion from Cold Bodies be made more strongly downwards, contrary to that of Hot Bodies: Where is delivered a way of freezing Liquors without danger of breaking the Vessel, by making them begin to freeze at the bottom, not the top.

6. Whether that Tradition be true, that if frozen Apples or Eggs be thaw'd neer the Fire, they will be thereby spoil'd, but if immersed in cold water, the Internal Cold will be drawn out, as is supposed, by the External Cold; and the frozen Bodies will be harmlesly thawed? Item, Whether Iron, or other Metals, Glass, Stone, Cheese, &c. expos'd to the freezing Air, or kept in Snow, or Salt, upon the immersing them in Water will produce any Ice? Item, What use may be made of what happens in the different waies of thawing Eggs and Apples, by applying the Observation to other Bodies, and even to Men, dangerously nipp'd by excessive Cold. Where is added not only a memorable Relation, how the whole Body of a Man was succesfully thawed and cased all over with Ice, by being handled, as frozen Eggs and Apples are; but also the Luciferousness of such Experiments, as these: and likewise, what the effects of Cold may be, as to the Conservation or Destruction of the Textures of Bodies: and in particular, how Meat and Drink {49} may be kept good, in very Cold Countries, by keeping it under Water, without glaciation? as also, how in extreme Cold Countries, the Bodies of Dead Men and other Animals may be preserved very many years entire and unputrified? And yet, how such Bodies, when unfrozen, will appear quite vitiated by the excessive Cold? Where it is further inquired into, whether some Plants, and other Medicinal things, that have specifique Vertues, will loose them by being throughly congealed and (several wayes) thawed? And also, whether frozen and thawed Harts-horn will yield the same quantity and strength of Salt and saline Spirit, as when unfrozen? Item, Whether the Electrical faculty of Amber, and the Attractive or Directive Virtue of Loadstones will be either impaired, or any wayes altered by intense Cold? This Head is concluded by some considerable remarks touching the operation of Cold upon Bones, Steel, Brass, Wood, Bricks.

7, What Bodies are expanded by being frozen, and how that expansion is evinced? And whether it is caused by the intrusion of Air? As also, whether, what is contained in icy bubbles, is true and Springy Air, or not.

8, What Bodies they are, that are contracted by Cold; and how that Contraction is evinced? Where 'tis inquired, whether Chymical Oyles will, by Congelation, be like expressed Oyls, contracted, or, like aqueous Liquors, expanded?

9, What are the wayes of Measuring the Quantity of the Expansion and Contraction of Liquors by Cold? And how the Author's account of this matter agrees with what Navigators into cold Climats, mention from experience, touching pieces of Ice as high as the Masts of their Ships, and yet the Depth of these pieces seems not at all answerable to what it may be supposed to be.

10, How strong the Expansion of freezing water is? Where are enumerated the several sorts of Vessels, which being filled {50} with water, and exposed to the cold Air, do burst; and where also the weight is expressed, that will be removed by the expansive force of Freezing? Whereunto an Inquiry is subjoyned, whence this prodigious force, observed in water, expanded by Glaciation, should proceed? And whether this Phaenomenon may be solved, either by the Cartesian, or Epicurean Hypothesis?

11, What is the Sphere of Activity of Cold, or the Space, to whose extremities every way the Action of a cold Body is able to reach: where the difficulty of determining these limits, together with the causes thereof, being with much circumspection mentioned, it is observed, that the Sphere of Activity of Cold is exceeding narrow, not only in comparison of that of Heat in Fire, but in comparison of, as it were, the Atmosphere of many odorous Bodies; and even in comparison of the Sphere of Activity of the more vigorous Loadstones, insomuch, that the Author hath doubted, whether the Sense could discern a Cold Body, otherwise then by immediate Contract. Where several Experiments are delivered for the examining of this matter, together with a curious relation of the way used in Persia, though a very hot Climate, to furnish their Conservatories with solid pieces of Ice of a considerable thickness: To which is added an Observation, how far in Earth and Water the Frost will pierce downwards, and upon what accounts the deepness of the Frost may vary. After which, the care is inculcated, that must be had, in examining, whether Cold may be diffused through all Mediums indefinitely, not to make the Trials with Mediums of two great thickness: where it is made to appear, that Cold is able to operate through Metalline Vessels, which is confirmed by a very pretty Experiment of making Icy Cups to drink in, whereof the way is accurately set down. Then are related the Trials, whether, or how, Cold will be diffused through a Medium, that some would think a Vacuum, and which to others would seem much less disposed to assist the diffusion of Cold, than Common Air it self. After which follows a curious Experiment, shewing whether a Cold Body can operate through {51} a Medium actually hot, and having its heat continually renewed by a fountain of heat.

12, How to estimate the solidity of the Body of Ice, or how strong is the mutual adhesion of its parts? and whether differing Degrees of Cold may not vary the Degree of the compactness of Ice. And our Author having proceeded as far as he was able towards the bringing the strength of Ice to some Estimate by several experiments, he communicateth the information, he could get about this matter among the Descriptions that are given us of cold Regions: and then he relateth out of Sea-mens Journals, their Observations touching the insipidness of resolved Ice made of Sea-water; and the prodigious bigness of it, extending even to the height of two hundred and forty Foot above water, and the length of above eight Leagues. To which he adds some promiscuous, but very notable Observations concerning Ice, not so readily reducible to the foregoing Heads: videlicet, Of the blew colour of Rocky pieces of Ice; and the horrid noise made by the breaking of Ice, like that of Thunder and Earthquakes, together with a Consideration of the cause, whence those loud Ruptures may proceed.

13, How Ice and Snow may be made to last long; and what Liquor dissolves Ice sooner than others, and in what proportion of quickness the Solutions in the several Liquors are made, where occasion is offered to the Author, to examine, whether Motion will impart a heat to Ice? After which he relates an Experiment of Heating a Cold Liquor with Ice, made by himself in the presence of a great and Learned Nobleman, and his Lady, who found the Glass wherein the Liquor was, so hot that they could not endure to hold it in their Hands. Next it is examined, whether the effects of Cold do continually depend upon the actual presence and influence of the manifest Efficient causes, as the Light of the Air depends upon the Sun or Fire, or other Luminous Bodies. To this is annexed an Account of the Italian way of making Conservatories of Ice and Snow, as the Author had received it from that Ingenious and Polite Gentleman, Master J. Evelyn. {52}

But want of time prohibiting the accomplishment of the intended account of this Rich Piece: what remains, must be referred to the next Occasion. It shall only be intimated for a Conclusion, that the Author hath annexed to this Treatise, an Examen of Master Hob's Doctrine touching Cold; wherein the Grand Cause of Cold and its Effects is assigned to Wind, in so much that 'tis affirmed, that almost any Ventilation and stirring of the Air doth refrigerate.

* * * * *

LONDON,

Printed with Licence, By John Martyn, and James Allestry, Printers to the Royal-Society, 1665

{53}

* * * * *



Numb. 4.

PHILOSOPHICAL TRANSACTIONS.

* * * * *

Munday, June 5. 1665.

* * * * *

The Contents.

A Relation of some extraordinary Tydes in the West Isles of Scotland, by Sr. Robert Moray. The judgment of Monsieur Auzout, touching the Apertures of Object-glasses, and their proportions in respect of the several lengths of Telescopes; together with a Table thereof. Considerations of the same Person upon Mr. Hook's New Engine for grinding of Optick-glasses. Mr. Hook's Thoughts thereupon. Of a means to illuminate an Object in what proportion one pleaseth; and of the distances, that are requisite to burn Bodies by the Sun. A further accompt by Monsieur Auzout of Signior Campani's Book, and Performances about Optick-Glasses. Campani's Answer thereunto; and Mr. Auzout's Animadversions upon that Answer. An accompt of Mr. Lower's newly published Vindication of Dr. Willis's Diatriba de Febribus.

* * * * *

A Relation of some extraordinary Tydes in the West-Isles of Scotland, as it was communicated by Sr. Robert Moray.

In that Tract of Isles, on the West of Scotland, called by the Inhabitants, the Long-Island, as being about 100. miles long from North to South, there is a multitude of small Islands, situated in a Fretum, or Frith, that passes between the Island of Eust, and the Herris; amongst which, there is one called Berneray, some three miles long, and {54} more than a mile broad, the length running from East to West, as the Frith lyes. At the East end of this Island, where I stayed some 16. or 17. dayes, I observed a very strange Reciprocation of the Flux and Re-flux of the Sea, and heard of another, no less remarkable.

Upon the West side of the Long Island, the Tides, which came from the South-west, run along the Coast, Northward; so that during the ordinary course of the Tides, the Flood runs East in the Frith, where Berneray lyes, and the Ebb West. And thus the Sea ebbs and flows orderly, some 4. days before the full Moon, and change, and as long after (the ordinary Spring-tides rising some 14. or 15. foot upright, and all the rest proportionably, as in other places). But afterwards, some 4. days before the Quarter-moons, and as long after, there is constantly a great and singular variation. For then, (a Southerly Moon making there the full Sea) the course of the Tide being Eastward, when it begins to flow, which is about 91/2 of the Clock, not onely continues so till about 31/2 in the afternoon, that it be high water, but, after it begins to ebb, the Current runs on still Eastward, during the whole Ebb; so that it runs Eastward 12 hours together, that is, all day long, from about 91/2 in the morning, til about 91/2 at night. But then, when the night-Tide begins to flow, the Current turns, and runs Westward all night, during both Floud & Ebb, for some 12. hours more, as it did Eastward the day before. And thus the Reciprocations continue, one Floud and Ebb, running 12 hours Eastward, and another twelve hours Westward, till 4. days before the New and Full Moon; and then they resume their ordinary regular course as before, running East, during the six hours of Floud, and West, during the six of Ebb. And this I observed curiously, during my abode upon the place, which was in the Moneth of August, as I remember.

But the Gentleman, to whom the Island belongs at present, and divers of his Brothers and Friends, knowing and discreet persons, and expert in all such parts of Sea-matters, as other Islanders commonly are, though I shrewdly suspected their skill in Tides, when I had not yet seen what they told me, and I have now related of these irregular Courses of the Tides, did most confidently assure me, and so did every body I spake with {55} about it, that there is yet another irregularity in the Tides, which never fails, and is no less extraordinary, than what I have been mentioning: which is, That, whereas between the Vernal and Autumnal Equinoxes, that is, for six Moneths together, the Course of irregular Tides about the Quartermoons, is, to run all day, that is, twelve hours, as from about 91/2 to 91/2, 101/4 to 101/4 &c. Eastward, and all night, that is, twelve hours more, Westward: during the other six Moneths, from the Autumnal to the Vernal Equinox, the Current runs all day Westward, and all Night Eastward.

Of this, though I had not the opportunity to be an Eye-witness, as of the other, yet I do not at all doubt, having received so credible Information of it.

To penetrate into the Causes of these strange Reciprocations of the Tides, would require exact descriptions of the Situation, Shape, and Extent of every piece of the adjacent Coasts of Eust and Herris; the Rocks, Sands, Shelves, Promontorys, Bays, Lakes, Depths, and other Circumstances which I cannot now set down with any certainty, or accurateness; seeing, they are to be found in no Map, neither had I any opportunity to survey them; nor do they now occur to my Memory, as they did some years ago, when upon occasion I ventured to make a Map of this whole Frith of Berneray, which not having copied, I cannot adventure to beat it out again.

* * * * *

_Monsieur Auzout_'s Judgment touching the Apertures of _Object-Glasses_, and their _Proportions_, in respect of the several _Lengths_ of _Telescopes_._

This Author, observing in a small French Tract lately written by him to a Countryman of his, Monsieur L' Abbe Charles; That great Optick Glasses have almost never as great an Aperture as the small ones, in proportion to what they Magnifie, and that therefore they must be more dim; takes occasion to inform {56} the Reader, that he hath found, that the Apertures, which Optick-Glasses can bear with distinctness, are in about a subduplicate proportion to their Lengths; whereof he tells us he intends to give the reason and demonstration in his Diopticks, which he is now writing, and intends to finish, as soon as his Health will permit. In the mean time, he presents the Reader with a Table of such Apertures; which is here exhibited to the Consideration of the Ingenious, there being of this French Book but one Copy, that is known, in England.

A TABLE of the Apertures of Object-Glasses.

The Points put to some of these Numbers denote Fractions.

Lengths of For excellent For good For ordinary Glasses. ones. ones. ones. Feet, Inches. Inch, Lines. Inch, Lines. Inch, Lines. 4 4. 4 3 6 5. 5 4 9 7 6 5 1 0 8. 7 6 - - - - 1 6 9 8. 7 2 0 11 10 8 2 6 1 0 11 9 3 0 1 1 1 0 10 - - - - 3 6 1 2. 1 1 11 4 0 1 4 1 2 1 0 4 6 1 5 1 3 1 . 5 0 1 6 1 4 1 1. - - - - 6 1 7. 1 5 1 2 7 1 9 1 6 1 3 8 1 10 1 8 1 4 9 1 11. 1 9 1 5 - - - - 10 2 1 1 10 1 6 12 2 4 2 0 1 8 14 2 6 2 2 1 9. 16 2 8 2 4 1 11. 18 2 10 2 6 2 1 20 3 0 2 7 2 2. - - - - 25 3 4 2 10 2 4. 30 3 8 3 2 2 7 35 4 0 3 4. 2 10 40 4 3 3 7 3 . - - - - 45 4 6 3 10 3 2. 50 4 9 4 0 3 4. 55 5 0 4 3 3 6. 60 5 2 4 6 3 8. - - - - 65 5 4 4 8 3 10 70 5 7 4 10 4 . 75 5 9 5 0 4 2. 80 5 11 5 2 4 5 - - - - 90 6 4 5 6 4 7. 100 6 8 5 9 4 10 120 7 5 6 5 5 3 150 8 0 7 0 5 11 - - - - 200 9 6 8 0 6 9 250 10 6 9 2 7 8. 300 11 6 10 0 8 5 350 12 *6. 10 9 9 0 400 13 4 11 6 9 8 - - - -



{57}

* * * * *

Considerations of Monsieur Auzout upon Mr. Hook's New Instrument for Grinding of Optick-Glasses.

In the above-mentioned French Tract, there are, besides several other particulars, to be represented in due place, contained some Considerations of Monsieur Auzout upon Mr. Hook's New Engine for grinding Optick-Glasses. Where he premises in General his thoughts touching the working of Great Optick-Glasses, and that by the help of a Turn lathe; affirming first of all, that not only the Engin is to be considered for giveing the Figure, but the Matter also, which ought to be brought to greater perfection, than it hath been hitherto. For, he finds it not so easie (as least, where he is) to procure Great pieces of Glass without Veins, and other faults, nor to get such, as are thick enough without Blebbs; which, if they be not, they will yield to the pressure and weight, either when they are fitted to the Cement, or wrought.

Secondly, He finds it difficult to work these Great Glasses of the same thickness, which yet is very necessary, because, that the least difference in Figures so little convex, can put the Center out of the Midle, 2 or 3 Inches; and if they be wrought in Moulds, the length of time, which is required to wear and to smooth them, may spoil the best Mould, before they be finished. Besides, that the strength of Man is so limited, that he is unable to work Glasses beyond a certain bigness, so as to finish and polish them all over so well, as small Glasses; whereas yet, the bigger they are, the more compleat they ought to be: And if any weight or Engine be used to supply strength, there is then danger of an unequal pressure, and of wearing away the Engine; In the mean time, the preciseness and delicateness is {58} greater than can easily be imagined. Wherefore he could never, having some experience of this preciseness, conceive, that a Turn-lathe, wherein must be two different, and in some manner contrary motions, can move with that exactness and steddiness, that is required, especially, for any considerable length of time.

Having premised this, he discourses upon Mr. Hook his Turne, intimating first of all, that he was impatient to know what kind of Turne this was, imagining, that it had been tried, and had succeeded, as coming from a Society that professeth, they publish nothing but what hath been maturely examin'd. But that he was much surprised when he saw the Micrography of Mr. Hook, and found there, that his Engine was published upon a meer Theory, without having made any Experiment, though that might have been made with little charge and great speed; expence of Money and Time being the onely thing, that can excuse those who in matter of Engines impart their inventions to the publick, without having tried them, to excite others to make trial thereof.

Whereupon he proposes some difficulties, to give the Inventor occasion to find a way to remove them. He affirms therefore, that though it be true in the Theory, that a Circle, whose Plain is inclined to the Axis of the Sphere by an Angle, whereof half the Diameter is the Sine, and which touches the Sphere in its Pole, will touch in all its parts a spherical Surface, that shall turn upon that Axe. But that it is true also, that that must be but a Mathematical Circle, and without Breadth, and which precisely touches the Body in its middle: Whereas in the practice, a Circle capable to keep Sand and Putty, must be of some breadth; and he knows not whether we can find such a dexterity of keeping so much of it, and for so long a time, as needs, upon the Brim of a Ring that is half an Inch broad. He adds, that it is very difficult to contrive, that the middle of the Glass do always precisely answer to the Brim of this Ring, seeing that the position of the Glass does always change a little in respect of the Ring, in proportion as 'tis worn, and as it must be pressed because of its inclination. He believes it also very hard, to give to the Axis or to the Mandril, which holds the Glass, that little {59} Inclination, that would be necessary for great Glasses, and to make the two Mandrils to have one and the same Plain, as is necessary. And, having done all this, he persuades himself, that it is exceedingly difficult, if not impossible, for two contrary motions, where so many pieces are, to rest for a long time steddy and firm, as is requisite for the not swarving from it a hair's thickness, since less than that can change all.

He goes on, and, seeing that this Inventor speaks of Glasses of a thousand, & ten thousand foot, which he supposed not impossible to be made by this Engine, discourses of what is necessary for the making Glasses of such bignesses; which he believes this Inventor may perhaps not have thought of. Wherefore he affirms, that if the Table, made by himself for the Apertures of Glasses (which is that, that is above delivered) be continued unto a thousand feet, by taking always the Subduplicate proportion of Lengths, it will be found, that for pretty good ones, the Aperture must be of 15. Inches; for good ones, more than 18. and for such as are excellent, more than 21. Inches: whence it may be judged, what piece of Glass, and of what thickness it must be, to endure the working. But he proceeds to speak of the Inclination, which the Mandril must have upon the Plain of the Ring, when the Ring should have 10. or 12 Inches; and finds, that it would make but 6 or 7. minutes of inclination, and that a Glass would have less Convexity, and consequently, less difference from a Glass perfectly plain, than the 7. or 8. part of a Line. And then he leaveth it to be judged, whether a Glass of such a Length being found, we ought to hope, that a Turn can be firm enough to keep such a piece of Glass in the same Inclination, so that a Mandril do not recede some Minutes from it: and, though even the Glass could be fastned perfectly perpendicular to the Mandril, that those two Mandrils could be put in one and the same Plain, & that that little Inclination, which is requisite, could be given, and the Mandril be continued to be pressed in that same Inclination, according as the Glass is worn. All which particulars, he conceives to be very hard in the practice; not to mention, that the weight of the Glass, that should be inclined to the Horizon, as 'tis represented by Mr. Hook, would make it slide upon the Cement, and so {60} change the Center; and that the Glass is not pressed at the same time by the Ring but in one part on the side, vid. about a fourth; and that the parts of the Glass are not equally worn away, &c. What then, saith he, would becom of a Glass of 10000 feet, which, according to the said Table, would have more than four feet, or four feet and nine inches, or five feet, seven inches Aperture, and of which the Ring, though it were two feet nine inches, would have but one minut of Inclination, and the Glass of 5 feet Aperture would have but 4 minuts, and the curvity of it would be less than the eight part of a Line.

But, saith he, let us consider, only a Glass of 300 foot, to see, what is to be hoped of that, and to know at least the difficulty, to be met with in making a Glass only of that Length. A Glass then of 300 foot, according to his Table, must have more than 8 inches Aperture, which maketh but 16 minuts of its Circle, and it should have more than 11 inches, if it be an excellent one. If Mr. Hook (adds he) did use but his Ring of 6 inches, which he would use from twelve to an hundred foot Glass, the Inclination, which the Axis, or Mandril, that bears his Glass, should have, should be but 16 minuts, and the Curvity of the Glass would be less than the eighth part of a Line, and if he should use a bigger, the Inclination would be proportionable.

Whence it may be judged (continues he) that we are yet very far from seeing Animals &c. in the Moon, as Monsieur Des Cartes gave hope, and Mr. Hook despairs not of. For, he believes by what he knows of Telescopes, that we are not to look for any above 300 or 400 foot at most; and he fears, that neither Matter nor Art will go even so far.

When therefore (saith he) a Glass of 300 foot should bear an Eye-glass of 6 inches (which would appear wonderful) it would magnifie but 600. times in Diameter, that is, 360000 times in Surface: but suppose, that such could be made, as would magnifie a 1000 times in Diameter, and 1000000. of times in Surface, admitting there were but 60000 leagues from the Earth to the Moon, and that the smalness of the Aperture of the Glasses (which yet would diminish the Light more than 36 times) and the obstacle of the Air were not considered, we should not {61} see the Moon, but as if we were a 100, or at least, 60. leagues distant from her without a Glass. He here wishes, that those, that promise to make us see Animals and Plants in the Moon, had thought on what our naked Eyes can make us discern of such Objects, only at 10 or 12 leagues distance.

But this he would not have understood as a discouragement from searching with all care and earnestness after the means of making long Telescopes, or of facilitating the working thereof; but only as an Advertisement to those, who light upon the Theory of any Engine, not to expose it presently as possible and useful, before they have tried it, or if it have succeeded in small, not to endeavour to persuade, that it will also succeed in great.

As it may happen (saith he) that the Engin of Mr. Hook may, by using all necessary precautions, succeed in the making of Eye-Glasses, or small Optick-Glasses, but not in making great ones; as we see, that an instrument composed of two Rulers, wherewith are traced Portions of Circles, succeeds well enough in small, but when there is no more than half a Line, a quarter of a Line, or less convexity, it will be no longer just at all, as he tells us to have made the proof of it in Circles drawn by the means of one of these Instruments, made by one of the best Workmen in his time, who, whilst he lived, esteemed them above price, although they be not just; as others and my self (saith he) have by tryal found, when we endeavoured to make Moulds by their means, & as those, who by the like Instrument laboured to trace portions of Circles of 80 or 100 foot, &c. Diameter, can attest.

But, notwithstanding all this, he hath thought upon two or three things, which he thinks may remedy some inconveniencies of Mr. Hook his Turn. The first is, to invert the Glass, and to put it under the Ring, that so not only the Glass may be placed more Horizontally, and not slide upon the Cement, but that the Sand also, and the Putty may stay upon the Glass.

The other is, that there must be two Poppetheads, into which the Mandril must pass, where the Ring is to be fastned; and the Mandril must be perfectly Cylindrical, that so it may advance upon the Glass as it wears away by the means of its weight, or by the means of a spring, pressing it, without wrigling from one place to another, as it would presently happen in the fashion, {62} as the Turn is composed. For, when the Glasses do wear, especially when they are very convex, it cannot be otherwise, but the Mandril will play and wrigle, before the Scrue be made firm.

But he doubts, whether all can be remedied, which he leavs to the industry of Mr. Hook, considering what he saith in the Preface of his Micrography, touching a Method, he knows, of finding out as much in Mechanicks, as can be found in Geometry by Algebra.

Besides this, he taketh notice, that most of those that medle with Optick-Glasses, give them not as much Aperture, nor charge them so deep as they ought. And he instances in the Telescope, which His Majesty of Great Britain presented the Duke of Orleans with, videl. that it did bear but 2 inches, and 9 lines French, for its greatest Aperture, though there be 5 or 6 lesser Apertures, of which it seems (saith he) the Artificer would have those, that use it, serve themselves more ordinarily, than of the greatest; which conveys but almost half as many Rays as it should do, according to his Calculation, which is, as 9 to 16; Whereas, according to his Table of Apertures, an excellent 35 foot Telescope should bear 4 inches Aperture in proportion to excellent small ones. He notes also, that the Eye-glass of the said Telescope, composed of 2 Glasses, hath no more effect, when it is most charged, than a Glass of 41/2 inches; which makes it magnifie not a 100 times. And he finds by Mr. Hook, that he esteems a Telescope made in London of 60 feet, (which amount to about 57 feet of France, the foot of France being to that of England as about 15 to 16) because it can bear at least 3 English inches Aperture, and that there are few of 30 feet, that can bear more than 2 inches, (which is but 221/2 Lines French) although he (M. Auzout) gives no less Aperture than so, to a 15 foot-Telescope, and his of 21 feet hath ordinarily 2 Inches, 4 Lines, or 2 inches, 6 Lines Aperture.

This Discourse he Concludeth with exhorting those, that work Optick-Glasses, to endeavor to make them such, that they may bear great Apertures and deep Eye-glasses; seeing it is not the length that gives esteem to Telescopes; but on the contrary renders them less estimable, by reason of the trouble {63} accompanying them, if they perform no more, than shorter ones. Where, by the by, he takes notice, that he knows not yet, what Aperture Signor Campani gives to his Glasses, seeing he hath as yet signified nothing of it; but that the small one, sent by him to Cardinal Antonio, hath no more Aperture, than ordinary ones ought to have.

He promises withall, that he will explicate this way in his Treatise of the usefulness of Telescopes, where he intends to assign the Bigness of the Diameter of all the Planets, and their proportion to that of the Sun; as also, that of the Stars, which he esteems yet much less, than all those have done, that have written of it hitherto; not believing, that the Great Dog, which appears to be the fairest Star of the Firmament, hath 2 Seconds in Diameter, nor that those, which are counted of the sixth Magnitude, have 20 thirds; nor thinking, that all the Stars, that are in the Firmament, do enlighten the Earth as much as a Luminous Body of 20 seconds in Diameter would do, or, because there is but one half of them at the same time above our Horizon, as a Body of 14 seconds in Diameter; and as the 18432^{th} part of the Sun would enlighten us, or as the Sun would do, if we were 14 times more distant from it, than Saturn, and 137 times further, than the Earth: Which, he saith, would not be credible, if he did not endeavor to evince it both by Experience and Reason. And he doubts not, but that Venus, although she sends us no Light but what is reflected, does sometimes enlighten the Earth more, than all the Stars together. Yet he would not have us imagine, from what he hath spoken of the smallness of the Stars, that Telescopes do not magnifie them by reason of their great distance, as they do Planets; for this he judgeth a Vulgar Error, to be renounced. Telescopes magnifie the Stars (saith he) as much in proportion, as they do all other Bodies, seeing that the demonstration of their magnifying is made even upon Parallel rays, which do suppose an infinite distance, though the Stars have none such: And if the Telescopes did not magnifie the Stars, how could they make us see some of the fiftieth, and it may be some of the hundreth, and twohundreth Magnitude, as they do, and as they would shew yet much lesser ones, if they did magnifie more? {64}

* * * * *

_M^r. Hook_'s Answer to Monsieur _Auzout_'s Considerations, in a Letter to the Publisher of these _Transactions_._

SIR,

Together with my most hearty thanks for the favour you were pleased to do me, in sending me an Epitome of what had been by the ingenious Monsieur Auzout animadverted on a description, I had made of an Engine for grinding spherical Glasses, I thought my self obliged, both for your satisfaction, and my own Vindication, to return you my present thoughts upon those Objections. The chief of which seems to be against the very Proposition it self: For it appears, that the Objector is somewhat unsatisfied, that I should propound a thing in Theory, without having first tried the Practicableness of it. But first, I could wish that this worthy Person had rectified my mistakes, not by speculation, but by experiments. Next, I have this to answer, that (though I did not tell the Reader so much, to the end that he might have the more freedom to examine and judg of the contrivance, yet) it was not meer Theory I propounded, but somewhat of History and matter of Fact: For, I had made trials, as many as my leisure would permit, not without some good success; but not having time and opportunity enough to prosecute them, I thought it would not be unacceptable to such, as enjoyed both, to have a description of a way altogether New, and Geometrically true, and seemingly, not unpracticable, whereof they might make use, or not, as they should see reason. But nothing surprised me so much, as, that he is pleased (after he had declared it a fault, to write this Theory, without having reduced it to practice) to lay it, as he seems to do, in one place of his book, p. 22 upon the Royal Society. Truly, Sir, I should think my self most injurious to that Noble Company, had I not endeavoured, even in the beginning of my Book, to prevent such a misconstruction. And therefore I cannot but make this interpretation of what Monsieur Auzout saith in this particular, that either he had not so {65} much of the Language wherein I have written, as to understand all what was said by me, or, that he had not read my Dedication to the Royal Society, which if he had done, he would have found, how careful I was, that that Illustrious Society should not be prejudiced by my Errors, that could be so little advantaged by my Actions. And indeed, for any man to look upon the matters published by their Order or Licence, as if they were Their Sense, and had Their Approbation, as certain and true, 'tis extremely wide of their intentions, seeing they, in giving way to, or encouraging such publications, aim chiefly at this, that ingenious conceptions, and important philosophical matter of Fact may be communicated to the learned and enquiring World, thereby to excite the minds of men to the examination and improvement thereof. But, to return; As to his Objections against the Matter, I do find that they are no more against mine, than any other way of Grinding Glasses; nor is it more than I have taken notice of my self in this Passage of the same Paragraph, of which sort are also those difficulties he raises about Long Glasses, which are commonly known to such, as are conversant in making them It would be convenient also (these are my words) and not very chargeable, to have four or five several Tools: One, &c. And, if curiosity shall ever proceed so farr, one for all lengths, between 1000. and 10000. foot long; for indeed, the Principle is such, that supposing the Mandrils well made, and of a good length, and supposing great care be used in working and polishing them, I see no reason, but that a Glass of 1000. nay, 10000. foot long may be made, as well as one of 10. For, the reason is the same, supposing the Mandrils and Tools be made sufficiently strong, so that they cannot bend; and supposing also that the Glass out of which they are wrought, be capable of so great a regularity in its parts, as to its Refraction. But next, I must say that his Objections to me, seem not so considerable, as perhaps he imagines them. For, as to the possibility of getting Plates of Glass thick and broad enough without veins, I think that not now so difficult here in England, where I believe is made as good, if not much better Glass for Optical Experiments, than ever I saw come from Venice. Next, though it were better, that the thickest part of a long Object-Glass were exactly in the middle, yet I can assure Monsieur Auzout, that it may be a very {66} good one, when it is an Inch or two out of it. And I have a good one by me at present, of 36. foot, that will bare an Aperture, if Saturn or the Moon in the twilight, be look'd on with it, of 31/2 Inches over, and yet the thickest part of the Glass is a great way out of the middle. And I must take the liberty to doubt, whether ever my Animadversor saw a long Glass, that was otherwise; as he might presently satisfie himself by a way I could shew him (if he did not know it) whereby the difference of the thickness of the sides might be found to the hundreth part of a Line.

As to the exceeding exactness of the Figure of Long Object-Glasses, 'tis not doubted, but that it is a matter difficult enough to be attained any way: but yet, I think, much easier by Engine, than by Hand; and of all Engines, I conceive, none more plain and simple, than that of a Mandril. And for making spherical Glasses by an Engine, I am apt to think, there hardly can be any way more plain, and more exact, than that which I have described; wherein there is no other motion, than that of two such Mandrils, which may be made of sufficient strength, length, and exactness, to perform abundantly much more, than I can believe possible to be done otherwise than by chance, by a man's hands or strength unassisted by an Engine, the motion and strength being much more certain and regular. I know very well, that in making a 60. foot Glass by the strength of the hand, in the common way, not one of ten that are wrought, will happen to be good, as I have been assured by Mr. Reeves; who, I am apt to think, was the first that made any good of that length. For the Figure of the Tool in that way is presently vitiated by the working of the Glass, and without much gaging will not do any thing considerable. Besides, the strength of a man's hands, applied to it for the working and polishing of it, is very unequal, and the motions made, are very irregular; but in the way, I have ventured to propose, by Mandrils, the longer the Glass and Tool are wrought together, the more exact they seem to be and if all things be ordered, as they should be, the very polishing of the Glass, does seem most of all rectifie the Figure.

As to what he objects, that the Tool does only touch the Glass in a Mathematical Circle; that is true, perhaps, at first, but before the Glass is wrought down to its true Figure, the Edge of the Tool {67} will be worn or grownd away, so as that a Ring of an inch broad may be made to touch the Spherical Surface of the Glass; nay, if it be necessary (without much trouble, especially in the grinding of longer Glasses) the whole Concave Surface of the Tool may be made to touch a Glass. Besides, that as to the keeping a quantity of the same sand and Powders of several finesses, according as the glass wears, the same is possible to be don, as with the same Sand wrought finer by working in the Ordinary way.

The giving the Inclination to the Mandrils, is not at all difficult; though perhaps to determine the length exactly which the Glass so made shall draw, is not so easie: But 'tis no matter, what length the Glass be off, so it be made good, whether 60 or 80 foot, or the like. Nor is it so very difficult, to lay them both in the same Plain. And to keep them steddy, when once fix'd, is most easie.

As to the Calculation of the propriety of a Glass of a thousand foot, perhaps for that particular Length, I had not, nor have as yet calculated, that the Convexity of one of eighteen inches broad, will not be above a seventh part of a Line. But it does not thence follow, that I had not considered the difficulties, that would be in making of it. For, I must tell him, that I can make a Plano convex Glass though its convexity be a smaler sphere than is usual for such a length to be an Object-Glass of about 150 foot in Length, nay of 300 foot, and either longer or shorter, without at all altering the convexity. So that, if he will by any Contrivance he hath, give me a Plano-convex Glass of 20, or 40 foot Diameter, without Veins, and truly wrought of that Figure, I will presently make a Telescope with it, that with a single Ey-glass shall draw a thousand foot: Which Invention, I shall shortly discover, there being, I think, nothing more easie and certain. And if a Plano-convex Glass can be made of any Sphere between twenty and fourty foot radius, so as that both the Convex and Plain side of the Glass be exactly polish'd of a true Figure, I will shortly shew, how therewith may be made a Telescope of any Length, supposing the Glass free from all kind of Veins, or inequality of Refraction.

As for the sliding of the Glass upon the Cement, I see no reason at all for it, at least in the Cement, I make use of, having never observed any such accident in hard Cement. {68}

And for the Bearing of the Ring against one side of the Glass only at a time, I cannot see, why that should produce any inequality, since all the sides of the Glass have successively the same pressure.

His ratiocination concerning a Glass of 300 foot, is much the same with the former, about the difficulty of working a true surface of a convenient figure; which how considerable both that and his Conclusion thereupon (videl. That we are not to expect Glasses of above 300 or 400 foot long at most, and that neither Matter nor Art will go so far) is, may be judged from what I have newly told you of making any Object-Glass of any Length.

And for his good wishes, that those, who promise to make him see Plants or Animals in the Moon (of which I know not any, that has done so, though perhaps there may be some, notwithstanding his Objections, that do not yet think it impossible to be done) had considered, what a Man is able to see with his bare Eye at 60 Leagues distance: I cannot but return him my wishes, that he would consider the difference between seeing a thing through the Gross and Vaporous Air neer the Earth, and through the Air over our heads: Which, if he observe the Moon in the Horizon, and neer the Zenith with a Telescope, he will experimentally find; and, having done so, he will perhaps not be so dissident in this matter.

Concerning his Advertisement to such, as publish Theories, I find not, that he hath made use of it in his own case. For, in his Theory about Apertures he seems to be very positive, not at all doubting to rely upon it, vid. that the Apertures must be thus and thus in great Glasses, because he had found them so or so in some small ones.

For his Proposal of amendments of some inconveniencies in this way, I return him my thanks; but as to his first I believe, that the matter may be conteined as wel in the Concave Tool, as on the convex Glass. And as to that of 2 Poppet-heads I do not well understand it, if differing from mine; and the keeping of the Tool upon the Glass with a spring or weight, must quickly spoyl the whole; since, if either of the Mandrils will easily yield backwards, the regularity of all will be spoiled: and as to the wrigling and playing of the Mandril, I do not at all apprehend it. {69}

His Theory of Apertures, though he seems to think it very authentick, yet to me it seems not so cleer. For, the same Glass will endure greater or lesser Apertures, according to the lesser or greater Light of the Object: If it be for the looking on the Sun or Venus, or for seeing the Diameters of the Fix'd Stars, then smaller Apertures do better; if for the Moon in the daylight, or on Saturn, or Jupiter, or Mars, then the largest. Thus I have often made use of a 12 foot-Glass to look on Saturn with an Aperture of almost 3 inches, and with a single Eye-glass of 2 inches double convex: but, when with the same Glass I looked on the Sun or Venus, I used both a smaller Aperture, and shallower Charge. And though M. Auzout seems to find fault with the English Glass of 36 foot, that had an Aperture of but 23/4 inches French; as also, with a 60 foot Tube, used but with an Aperture of 3 inches; yet I do not find, that he hath seen Glasses of that length, that would bear greater Apertures, and 'tis not impossible, but his Theory of Apertures may fail in longer Glasses.

* * * * *

Of a means to illuminate an Object in what proportion one pleaseth; and of the Distances requisite to burn Bodies by the Sun.

One of the means used by M. Auzout to enlighten an Object, in what proportion one pleaseth, is by some great Object-Glass, by him called a Planetary one, because that by it he shews the difference of Light, which all the Planets receive from the Sun, by making use of several Apertures, proportionate to their distance from the Sun, provided that for every 9 foot draught, or thereabout, one inch of Aperture be given for the Earth. Doing this, one sees (saith he) that the Light which Mercury receives, is far enough from being able to burn Bodies, and yet that the same Light is great enough in Saturn to see cleer there, seeing that (to him) it appears greater in Saturn, than it doth upon our Earth, when it is overcast with Clouds: Which (he adds) would scarce be believed, if by means of this Glass it did not sensibly appear so; Whereof he promises to discourse more fully in his {70} Treatise of the usefulness of great Optick-Glasses, where he also intends to deliver several Experiments, by him made, 1. Touching the quantity of Light, which a Body, that is 10, 15 and 20 times, &c. remoter than Saturn, would yet receive from the Sun. 2. Touching the quantity of Light, by which the Earth is illuminated even in the Eclipses of the Sun, in proportion of their bigness. 3. Touching the quantity of Light, which is necessary to burn Bodies: he having found, that not abating the Light, which is reflected by the Surfaces of the Glass (whereof he confesseth, he doth not yet exactly know the quantity) there would be necessary about 50 times as much Light, as we have here, for the burning of Black Bodies; and neer 9 times more for the burning of White Bodies, than for the burning of Black ones: and so observing the immediate proportions between these two, for burning bodies of other Colors. Whence (he tells us) he hath drawn some consequences, touching the distance, at which we may hope, to burn Bodies here, by the means of great Glasses and great Looking-glasses. So that (saith he) we must yet be seven times neerer the Sun, than we are, to be in danger of being burned by it. Where he mentions, that having given Instructions to certain persons, gon to travel in Hot Countries, he hath among other particulars recommended to them, to try by means of great Burning-glasses, with how much less Aperture they will burn there, than here, to know from thence, whether there by more Light there than here, and how much; since this perhaps may be the only means of trying it, supposing, the same matters be used: although the difference of the Air already heated, both in hot Countries, and in the Planets, that are neerer than we, may alter, if not the quantity of Light, at least that of the Heat, found there.

* * * * *

A further Account, touching Signor Campani's Book and Performances about Optick-glasses.

In the above-mentioned French Tract there is also conteined M. Auzout's Opinion of what he had found New in the Treatise of Signor Campani, which was spoken of in the first Papers of these Transactions, concerning both the Effect of the Telescopes, contrived after a peculiar way by the said Campani at Rome, and {71} his New Observations of Saturn and Jupiter, made by means thereof.

First therefore, after that M Auzout had raised some scruple against the Contrivance of Signor Campani for making Great Optick-Glasses without Moulds, by the means of a Turn-lath, he examines the Observations, made with such Glasses: Where, having commended Campani's sincerity in relating what he thought to have seen in Saturn, without accomodating it to M. Hugens's Hypothesis, he affirms, that supposing, there be a Ring about Saturn, Signor Campani could not see in all those different times, that he observed it, the same Appearances, which he notes to have actually seen. For, having seen it sometimes in Trine Aspect with the Sun, and Oriental; sometimes, in the same Aspect, but Occidental; sometimes in Sextil Aspect, and Occidental; at another time, again in Trine, and Oriental, this Author cannot conceive, how Saturn could in all these different times have no difference in its Phasis, or keep always the same Shadow; seeing that, according to the Hypothesis of the Ring, when it was Oriental, it must cast the Shadow upon the left side of the Ring beneath, without casting any on the right side: and when it was Occidental, it could not but cast it on the right side beneath, and nothing of it on the other.

Concerning the Shadow above, which Campani affirms to be made by the Ring upon the Body of Saturn, M. Auzout judges, that there could be no such Phaenomenon, by reason of its Northern Latitude at the times, wherein the Observations were made, vid. in April 1663; in the midst of August, and the beginning of October, next following, and in April 1664, except it were in October, and the Shadow strong enough to become visible.

But as to the Shadow below, he agrees with Campani, that it does appear, yet not as he notes it, seeing that it must be sometimes on the one side, sometimes on the other; and towards the Quadrat with the Sun it must appear biggest, as indeed he affirms to have seen it himself this year, insomuch that sometimes it seemed to him, that it covered the whole Ring, and that the Shadow, joyning with the obscure space between both, did interrupt the circumference of the Ring; but beholding it at other times in a cleer Sky, and when there was no Trepidation of the Air, {72} he thought, that he saw also the Light continued from without, although very slender. But he acknowledges, that he could never yet precisely determine, by how much the largeness of the Ring was bigger than the Diameter of Saturn's Body. As for the proportion of the Length to the Breadth, he affirms, to have alwaies estimated it to be two and a half, or very neer so; and to have found in his Observations, that in January last, one time, the length of Saturn was 12 Lines, and the breadth 5. Another time, the length was 12. Lines, and the breadth 4. and this by a peculiar method of his own. But yet he acknowleges also, that sometimes he hath estimated it as 7. to 3. and at other times as 13. to 5. and that if there do not happen a change in the magnitude of the Ring (as it is not likely there does) that must needs proceed from the Constitution of the air, or of the Glass's having more or less Aperture, or from the difficulty of making an exact estimate of their proportions. However it is not much wide (saith he) of two and a half, although Campani make the length of the Ring but double to its breadth.

Monsieur Auzout believes, that he was one of the first that have well observed this shadow of Saturn's Body upon its Rings which he affirms happened two years since; when, observing in July, for the first time, with a Telescope of 21. and then another of 27. foot, he perceived, that the Angle of the obscure space on the right side beneath, was bigger and wider, than the three other Angles, and that some interruption appear'd there, between the Ring, and the Body of Saturn; of which he saith to have given notice from that time to all his friends, and in particular, as soon as conveniently he could, to Monsieur Hugens.

He confesseth, that he hath not had the opportunity of observing Saturn in his Oriental Quadrat; yet he doubts not, but that the shadow appears on the Left-side, considering, that the Existence of the Ring can be no longer doubted of, after so many Observations of the shadow cast by Saturn's Body upon it, according as it must happen, following that Hypothesis; there being no reason, why it should cast the said shadow on one side, and not on the other.

Concerning the Observation of Jupiter and its satellites, the famous Astronomer of Bononia, Cassinus, having {73} published, that on the 30. day of July, 1664. at 21/2 of the clock in the morning, he had observ'd, with Campani's Glasses, that there passed through the broad obscure Belt of Jupiter two obscurer spots, by him esteemed to be the shadows of the Satellites, moving between Jupiter & the Sun, and eclipsing him, and emerging from the Occidental Brim thereof: This Authour did first conceive, that they were not shadows, but some Sallies, or Prominencies in that Belt; which he was induced to believe, because he perceived not, that that Prominency, which he there saw, was so black, nor so round as Cassini had represented his spots; wherefore, seeing it but little differing in colour, from the Belt, and so not judging it round, because it did stand only about half its diameter out of the Belt, he persuaded himself, that it was rather a Sally, or Prominency of the Belt, than a round shadow, as that of a Satellite of Jupiter must have bin. But having been since informed of all the Observations made by Cassini and Campani, with the New Glasses, and seen his Figure, he candidly and publickly wisheth, that he had not spoken of that Sally, or Prominency; advowing that he can doubt no longer, but that it was the shadow of the Satellit between Jupiter and the Sun, having seen the other emerge, as soon as with a 20. foot Glass he made the Observation, and having not perceiv'd these shadows with a 12. foot Glass: But although he grants that they did ghess better than he, yet he doth it with this proviso, vid. in case they made that Observation on of July 30. not with their 36. but 12. or 17. foot Telescope. If it be wondred at, that Monsieur Auzout did not see this shadow move, he allegeth his indisposition for making long Observations, and addeth, that it may be much more wondred at, that neither Campani nor himself did see upon the obscure Belt the Bodies of the Satellites, as parts more Luminous than the Belt. For (saith he) although the Latitude was Meridional, it being no more than of 9. or 10. minutes, the Body of the Satellites should, thinks he, pass between us and the Belt, especially according to Campani, who maketh the Belt so large, and puts the shadows farr enough within the same. This maketh him conclude, that either they have not observed well enough, or that the motion of the Satellites doth not exactly follow the Belts, and is inclin'd unto them. Whereupon he resolves, that when he shall know that they are to pass between Jupiter and us, and to be over against the Belt, that {74} then he will observe, whether he can see them appear upon the Belt, as upon a darker ground, especially, the third of them, which is sensibly greater, and more Luminous, than the rest. He hopeth also, that in time, the shadow of Saturns Moon will be seen upon Saturn, although we are yet some years to stay for it, and to prepare also for better Glasses.

From this rare Observation, he inferrs the Proportion of the Diameter of the Satellites to that of Jupiter; and judgeth, that no longer doubt can be made of the turning of these 4. Satellites, or Moons about Jupiter, as our Moon turns about the Earth, and after the same way as the rest of the Celestial Bodies of our Systeme do move: whence also a strong conjecture may be made, that Saturns Moon turns likewise about Saturn.

Hence he also taketh occasion to intimate, that we need not scruple to conclude, that if these two Planets have Moons wheeling about them, as our Earth hath one that moves about it, the conformity of these Moons with our Moon, does prove the conformity of our Earth with those Planets, which carrying away their Moons with themselves, do turn about the Sun, and very probably make their Moons turn about them in turning themselves about their Axis; and also, that there is no cause to invent perplex'd and incredible Hypotheses, for the receding from this Analogie since (saith he) if this be truth, the Prohibitions of publishing this doctrine, which formerly were caused by the offence of Novelty, will be laid aside, as one of the most zealous Doctors of the contrary Opinion hath given cause to hope, witness Eustachius de Divinis, in his Tract against Monsieur Hugen's Systeme of Saturn, p. 49. where we are inform'd, that that learned Jesuit, P. Fabry, Penitentiary of S Peter in Rome, speaks to this purpose:

Ex vestris, iisque Coryphaeis non semel quaesitum est, utrum aliquam haberent demonstrationem pro Terrae motu adstruendo. Nunquam ausi sunt id asserere Nul igitur obstat quin loca illa in sensu literali Ecclesia intelligat, & intelligenda esse declaret, quamdiu nulla demonstratione contrarium evincitur; quae si forte aliquando a vobis excogitetur (quod vix crediderim) in hoc casu nullo modo dubitabit Ecclesia declarare, loca illa in sensu figurato & improprio intelligenda esse, ut illud Poetae, Terraeque Urbesque recedunt.

It hath been more than once asked of your Chieftains, whether they had a Demonstration for asserting the motion of the Earth? They durst never yet affirm they had; wherefore nothing hinders, but that the Church may understand those Scripture-places, that speak of this matter, in a literal sence, and declare they should be so understood, as long as the contrary is not evinced by any demonstration; {75} which, if perhaps it should be found out by you (which I can hardly believe it wil) in this case the Church will not at all scruple to declare, that these places are to be understood in a figurative and improper sence, according to that of the Poet, Terraeque Urbesque recedunt.

Whence this Author concludes, that the said Jesuite assuring us that the inquisition hath not absolutely declared, that those Scripture-places are to be understood literally, seeing that the Church may make a contrary declaration, no man ought to scruple to follow the Hypothesis of the Earths motion, but only forbear to maintain it in publick, till the prohibition be called in. But to return to the matter in hand, this Author, upon all these observations and relations of Cassini and Campani, doth find no reason to doubt any more of the excellency of the Glass used by them, above his; except this difference may be imputed to that of the Air, or of the Eys. But yet he is rather inclined to ascribe it to the goodness of their Glasses, and that the rather, because, he would not be thought to have the vanity of magnifying his own; of which, yet he intimates by the by, that he caused one to be wrought, of 150 Parisian feet; which though it proved none of the best, yet he despairs not to make good ones of that, and of far greater Length.

* * * * *

_Signor Campani's_ Answer: and Monsieur _Auzout_'s Animadversions thereon._

The other part of this French Tract, conteining Campani's Answer, and Mr. Auzout his Reflections thereon, begins with the pretended Shadows of the Ring upon Saturn, and of Saturn upon the Ring. Concerning which, the said Campani declareth, that he never believed them to be shadows, made by the Ring upon the Disk of Saturn, or by the body of Saturn upon the Ring, but the Rimms of these bodies, which being unequally Luminous, did shew these appearances. In which Explication, forasmuch as it represents, that the said Campani meant to note only the Inequality of the Light, which, he saith, his Glasses did discover, Mr. Auzout does {76} so far acquiesce, that he only wishes, that his own Glasses would shew him those differences. Next to the Objection, made by Monsieur Auzout, against Signor Campani, touching the Proportion of the Length of the Ring to its breadth, Campani replyeth, that the Glasses of Monsieur Auzout, shew not all the particulars, that his do, and therefore are unfit for determining the true Figure and breadth of the apparent Ellipsis of the Ring. To which M. Auzout rejoyns, that he is displeased at his being destitute of better Glasses, but that it will be very hard for the future to convince Campani touching the Proportion of the Ring, seing that the breadth of the Ellipsis is always diminishing, although, if the declination of the Ring remains always the same, one can at all times know, which may have been its greatest breadth. But he assures, that the breadth of the Ring is not the half of its length, and that it doth not spread out so much beyond Saturn's Body, as he hath alleged. And withal desirs to know, what can be answered by Sig. Campani to M. Hugens, who being persuaded, that the Declination of the Ring is not above 23 deg. 30' having seen the Ring to spread out above the Body of Saturn, concludes, in a Letter to M. Auzout, that the length of the Ring is more than treble the Diameter of Saturn's body, which, according to Campani, is only as about 67 to 31. Which difference yet dos not appear to M. Auzout to be so great; but that M. Hugens perhaps will impute it to the Optical reason, which he (Auzout) hath alleged of the Advance of the light upon the obscure space; although he is of Opinion, he should not have concluded so great a Length, if he had not seen the Breadth spread out more, than he hath done: for (saith he) if the Length of the Ring be to the body of Saturn, 21/2 to 1. and the Inclination be 23 deg. 30' the Ring will be just as large, as the body, without spreading out; but if the Ring be bigger, it will a little spread out; and if it were treble, it must needs spread out the half of its breadth, which hath not so appeared to him.

Further, to M. Auzout's change of Opinion, and believing, that the Advance or Sally, seen by him in Jupiter, was the Shadow of one of his Moons, Campani declares, that he would not have him guilty of that change: Whereupon M. Auzout wonders, why Campani then hath not marked it in his Figure; and would {77} gladly know, whether that Sally be more easie to discover, than the Shadows of the Satellites, which Campani believs, Auzout hath not seen; and whether he be assured, that those obscure parts, which he there distinguishes, do not change: for if they should not change, then Jupiter would not turn about his Axis, which yet, he saith, it doth, according to the Observation made by Mr. Hook, May 9 1664. inserted in the first papers of these Transactions. The full Discovery of which particular also he makes to be a part of Cassini's and Campani's work, seeing that they so distinctly see the inequalities in the Belts, and see also sometimes other Spots besides the Shadows of the Satellites: where he exhorts all the Curious, that have the conveniency of observing, to endeavor the discovery of a matter of that importance, which would prove one of the greatest Analogies for the Earth's Motion.

* * * * *

An Account of Mr. Richard Lower's newly published Vindication of Doctor Willis's Diatriba de Febribus.

The Title of this Curious piece, is Diatribae Thomae Willisii Med. Doct. & Profess. Oxon. De Febribus Vindicatio, Authore Richardo Lower, &c. In it are occasionally discussed many considerable Medical and Anatomical inquiries, as, Whether a Fever does consist in an Effervescence of Blood? And if so, of what kind? Whether there be a Nervous and Nutritious Juice? Whether the office of sanguification belongs to the Blood it self, existing before those Viscera (at least) that are commonly esteemed to be the Organs of sanguification? How Nutrition is performed, and the nourishing substance assimilated? Whether the Blood affords both the Matter for the structure of the Body, and such parts also, as are fit for the nourishment of the same? Whether the Pulse of the Heart ceasing, there remains yet a certain Motion in the blood, arguing, that Pulse and Life do ultimately rest in the Blood? Whether the Umbilical Vessels convey the blood of the Mother to the Child, or whether the Foetus be for the most part form'd and {78} acted by the circulating blood, before the existence of the Umbilical Vessels, or before the connecting of the Foetus with the Uterus? A new Experiment to prove that the Chyle is not transmuted into Blood by the Liver. A discourse of the Nature of the Blood, and what difference there is between the Venal and Arterial blood, and for what Uses both the one and the other are particularly designed. Where it is considered, what Life is, and whence the Soul of Brutes, and its subsistence, and operations do depend. It is also inquired into, what the uses of the Lungs are in hot Animals? And many other such material disquisitions are to be found in this small, but very Ingenious and Learned Treatise.

* * * * *

A Note touching a Relation, inserted in the last Transactions.

In the Experiment of killing Ratle-Snakes, mentioned in the last of the precedent Papers (wherein, by a mistake, these words, The way, were put for A way, or An Experiment) it should have been added, that the Gentleman there mention'd, did affirm, that, in those places, where the Wild Penny-Royal or Dittany grows, no Ratle-Snakes are observed to come.

* * * * *

Errata.

Pag. 59. line 11. read, bignesses, l. 20. r. endure, for, resist. l. 30. r. those, for, these. l. 31. r. Plain, for, place.

* * * * *

LONDON,

Printed with Licence, By John Martyn, and James Allestry, Printers to the Royal-Society, at the Bell in St. Pauls Church-Yard. 1665.

{79}

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Numb. 5.

PHILOSOPHICAL TRANSACTIONS.

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Munday, July 3. 1665.

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The Contents.

An Account, how Adits and Mines are wrought at Liege without Air-shafts, communicated by Sir Robert Moray. A way to break easily and speedily the hardest Rocks; imparted by the same Person, as he received it from Monsieur Du Son the Inventor. Observables upon a Monstrous Head. Observables in the Body of the Earl of Belcarres, sent out of Scotland. A Relation of the designed Progress to be made in the Breeding of Silk-worms, and the Making of Silk, in France. Enquiries touching Agriculture, for Arable and Meadows.

* * * * *

An Account, how Adits & Mines are wrought at Liege without Air-shafts, communicated by Sir Robert Moray.

It is well known to those conversant in Mines, that there is nothing of greater inconvenience in the working or driving, as they call it, of Mines or Adits under ground, for carrying away of Water, or such Minerals as the Mine affords, than the Damp, want, and impurity of Air, that {80} occur, when such Adits are wrought or driven inward upon a Level, or near it, 20, 30, or 40. fathom, more or less. Aswel because of the expence of money, as of time also, in the Ordinary way of preventing or remedying those inconveniences; which is, by letting down shafts from the day (as Miners speak) to meet with the Adit; by which means the Air hath liberty to play through the whole work, and so takes away bad vapours and furnishes good Air for Respiration. The Expence of which shafts, in regard of their vast depth, hardness of the Rock, drawing of water, &c. doth sometimes equal, yea exceed the ordinary charge of the whole Adit.

Amongst the Expedients that have been devised to remedy this, there is one practised in the Coal-mines, near the Town of Liege (or Luyck) that seems preferable to all others for Efficacy, Ease, and Cheapness: the description whereof followeth.

At the mouth or entry of the Adit there is a structure raised of Brick, like a Chimney, some 28. or 30. foot high in all: at the bottom, two opposite sides are (or may be) some 51/2 foot broad; and the other two, 5. foot: the wall 11/2 Brick thick. At the lower part of it, is a hole, some 9. or 10. inches square, for taking out of the Ashes, which when it is done, this Ash-hole is immediately stopt so close, as Air cannot possibly get in at any part of it. Then, some 3. foot above ground or more, there is on that side, that is next to the Adit or Pit, a square hole of 8. or 9. inches every way, by which the Air enters to make the Fire burn: Into this hole there is fixed a square Tube or Pipe of Wood, whereof the Joints and Chinks are so stopt with Parchment pasted or glewed upon them, that the Air can no where get in to the Pipe but at the end: And this Pipe is still lengthened, as the Adit or Pit advanceth, by fitting the new Pipes so, as one end is alwaies thrust into the other, and the Joints and Chinks still carefully cemented and stopt as before. So the Pipe or Tube being still carried on, as near as is necessary, to the wall or place, where fresh Air is requisite; the Fire within the Chimney doth still attract {81} (so to speak) Air through the Tube, without which it cannot burn, which yet it will do, as is obvious to conceive (all Illustrations and Philosophical Explications being here superfluous,) and so, while the Air is drawn by the fire from the farthest or most inward part of the Mine or Adit, fresh Air must needs come in from without to supply the place of the other, which by its motion doth carry away with it all the ill vapors, that breath out of the ground; by which meanes the whole Adit will be alwaies filled with fresh Air, so that men will there breath as surely as abroad, and not only Candles burn, but Fire, when upon occasion there is use for it for breaking of the Rock.

Now that there may be no want of such fresh Air, the Fire must alwaies be kept burning in the Chimney, or at least as frequently as is necessary: For which purpose there must be two of the Iron Grates or Chimneys, that when any accident befals the one, the other may be ready to be in its place, the Coals being first well kindled in it: but when the fire is neer spent, the Chimney or Grate being haled up to the dore, is to be supplied with fresh fuel.

The Figure of the Fabrick, Chimney, and all the parts thereof being hereunto annexed, the rest will be easily understood.



Figure 1.

A. The Hole for taking out the Ashes.

B. The Square-hole, into which the Tube or Pipe for conveying the Air is to be fixed.

C. The Border or Ledge of Brick or Iron, upon which the Iron-grate or Cradle, that holds the burning Coals, is to rest, the one being exactly fitted for the other.

D. The Hole where the Cradle is set.

E. The woodden Tube, through which the Air is conveyed towards the Cradle.

F. The Dore, by which the Grate and Cradle is let in, which is {82} to be set 8. or 10. foot higher than the Hole D. and the Shutter made of Iron, or Wood that will not shrink, that it may shut very close, this Dore being made large enough to receive the Cradle with ease.

G. The Grate or Cradle, which is narrower below than above, that the Ashes may the more easily fall, and the Air excite the Fire; the bottom being barred as the sides.

H. The Border or Ledge of the Cradle, that rests upon the Ledge C.

I. Four Chains of Iron fastned to the four corners of the Cradle, for taking of it up, and letting of it down.

K. The Chain of Iron, to which the other are fastned.

L. The Pulley of Iron or Brass, through which the Chain passeth.

M. A Hook, on which the end of the Chain is fastned by a Ring, the Hook fixed being placed in the side of the Dore.

N. A Barr of Iron in the Walls, to which the Pulley is fastned.

The higher the Shaft of the Chimney is, the Fire draws the Air the better. And this Invention may be made use of in the Pits or Shafts, that are Perpendicular, or any wise inclining towards it, when there is want of fresh Air at the bottom thereof, or any molestation by unwholsom Fumes or Vapors:

* * * * *

A way to break easily and speedily the hardest Rocks, communicated by the same Person, as he received it from Monsieur Du Son, the Inventor.



Though the invention of breaking with ease, and dispatch, hard Rocks, may be useful on several occasions, the benefit is incomparably great, that may thereby accrue to those, who have Adits or Passages to cut through hard Rocks, for making passage for Water to run out by, in Mines of Lead, Tin, or any other whatsoever; these Adits appearing to be the surest, cheapest, and most advantagious way imaginable, for draining of the same. {83}

That which is here to be described, was invented by one of the most Excellent Mechanicks in the World, Monsieur du Son, who lately put it in practice himself in Germany, at the desire of the Elector of Mentz. The manner is, as followeth.

The Mine or Adit is to be made seven or eight foot high, which though it seem to make more work downwards, yet will be found necessary for making the better dispatch by rendring the Invention more effectual.

There is a Tool or Iron well steeled at the end, which cuts the Rock, (of the shape shewed by Fig. 2. here annexed,) 20. or 22. Inches long or more, and some 21/2 Inches Diameter at the steeled end, the rest being somewhat more slender. The steeled end is so shaped, as makes it most apt to pierce the Rock, the Angles at that end being still to be made the more obtuse, the harder the Rock is. This Tool is to be first held by the hand, in the place, where the Hole, to be made for the use, which shall here be shewed, is to be placed; that is, in the middle between the sides of the Rock, that is to be cut, but as near the bottom as may be. The Tool being placed, is to be struck upon with an Hammer, the heavier the better, either suspended by a Shaft turning upon a Pin, or otherwise, so as one man may manage the Hammer, while another holds the Tool or Piercer. If it be hung in a Frame, or other convenient way, he that manageth it hath no more to do, but to pull it up at first as high as he can, and let it fall again by its own weight, the motion being so directed, as to be sure to hit the Piercer right. After the stroke of the Hammer, he that holds the Piercer, is to turn it a little on its point; so that the Edges or Angles at the point may all strike upon a new place; and so it must still be shifted after every stroke, by which means small Chipps will at every stroke be broken off, which must from time to time be taken out, as need requires. And thus the work must be continued, till the Hole be 18. or 20. Inches deep, the deeper the better. This Hole being made as deep as is required, and kept as streight and smooth in the sides, as is possible, there is then a kind of double Wedge to be made, and {84} fitted exactly for it; the shape whereof is to be seen in the annexed 3. Figure.



This double Wedge, being 12. or 13. Inches long, each piece of it, and so made, as being placed in their due position they may make up a Cylinder, but Diagonal-wise. The two flat sides that are contiguous, are to be greased or oyled, that the one may slip the more easily upon the other; and one of them, which is to be uppermost, having at the great end a hollow Crease cut into it round about, for fastening a Cartridge, full of Gunpowder, to it with a thred, the round end of the Wedge being pared as much as the thickness of the Paper or Pastboard, that holds the Powder, needs to make the outside thereof even with the rest of the Wedge. This Wedge must have an Hole drilled through the longest side of it, to be filled with priming Powder, for firing of the Powder in the Cartridge; which needs have no more, than half a pound of Powder, though upon occasion a greater quantity may be used, as shall be found requisite.

Then this Wedge, being first thrust into the Hole with the Cartridge, the round side, whether the Priming-hole is, being uppermost, the other Wedge is to be thrust in, home to the due position, care being taken, that they fit the Hole in the Rock as exactly as may be. Then the end of the lower Wedge being about an Inch longer, than that of the upper outwardly, and flatned, priming Powder is to be laid upon it; and a piece of burning Match or Thread dipt in Brimstone or other such prepared combustible Matter, fastned to it, that may burn so long before it fire the Powder, as he, that orders it, may have time enough to retire quite out the Pit or Adit, having first placed a piece of Wood or Iron so, as one end thereof, being set against the end of the lower Wedge, and the other against the side-wall, so as it cannot slip. Which being done, and the Man retired, when the Powder comes to take fire, it will first drive out the uppermost Wedge, as far as it will go, but the slaunting figure of it being so made, as the farther it goes backward, the thicker it grows, till at the last it can go no farther, then the {85} fire tears the Rock to get forth, and so cracks and breaks it all about, that at one time a vast deal of it will either be quite blown out, or so crackt and broken, as will make it easie to be remov'd: And according to the effect of one such Cartridge, more may be afterwards made use of, as hath been said.

* * * * *

Observables upon a Monstrous Head.



This was the Head of a Colt, represented in the annexed Figure 4. first viewed by Mr. Boyle, who went into the Stable where the Colt lay, and got the Head hastily and rudely cut off, the Body thereof appearing to his Eye compleately formed, without any Monstrosity to be taken notice of in it. Afterwards he caused it to be put into a Vessel, and covered with Spirit of Wine thereby chiefly intending, to give good example, together with a proof, that by the help of the said Spirit, (which he hath recommended for such Properties in one of his Essays of the Usefulness of Natural Philosophy) the parts of Animals, and even Monsters, may in Summer it self be preserved long enough to afford Anatomists the opportunities of examining them.

The Head being opened, and examined, it was found.

First, That it had no sign of any Nose in the usual place, nor had it any, in any other place of the Head, unless the double Bag CC, that grew out of the midst of the forehead, were some rudiment of it.

Next, That the two Eyes were united into one Double Eye, which was placed just in the middle of the Brow, the Nose being wanting, which should have separated them, whereby the two Eye-holes in the Scull were united into one very large round hole, into the midst of which, from the Brain, entred one pretty large Optik Nerve, at the end of which grew a great Double Eye; that is, that Membrane, called Sclerotis, which contained both, was one and the same, but seemed to have a Seam, {86} by which they were joined, to go quite round it, and the fore or pellucid part was distinctly separated into two Cornea's by a white Seam that divided them. Each Cornea seemed to have its Iris, (or Rain-bow-like Circle) and Apertures or Pupils distinct; and upon opening the Cornea, there was found within it two Balls, or Crystalline Humours, very well shaped; but the other parts of it could not be so well distinguished, because the eye had been much bruised by the handling, and the inner parts confused and dislocated. It had four Eye-browes, placed in the manner exprest in Figure 4. by a a, b b; a a representing the lower, and b b, the upper Eye-lids.

Lastly, That just above the Eyes, as it were in the midst of the Forehead, was a very deep depression, and out of the midst of that grew a kind of double Purse or Bagg, C C, containing little or nothing in it; but to some it seemed to be a production of the matter designed for the Nose, but diverted by this Monstrous Conception; perhaps the Processus mammillares joyned into one, and covered with a thin hairy skin.

* * * * *

Observables in the Body of the Earl of Balcarres.

These following Observations, were a while since sent out of Scotland by an ingenious person, an Eye-witness, to Sir Robert Moray.

1. That the Belly of this Nobleman being opened, the Omentum or Net was found lean and small: his Liver very big; the Spleen big also, filled with a black and thick humour. His Stomack and Entralls all empty, of a Saffron-colour, distended with wind only. The Bladder of Gall swelled with a black humour: The Kidneys filled with a kind of grumous blood.

2. That in the Thorax or Chest, the Lobes of the Lungs were all entire, but of a bad colour; on the left side somewhat black and blue, and on the right, whitish; with a yellowish knob under one of the Lobes. {87}

3. That the Pericardium or the Case of the Heart being opened, there appeared none of that water, in which the Heart uses to swim; and the external Surface of it, from the Base to the Tipp, was not smooth, but very rough. It being cut asunder, a quantity of white and inspissate liquour run out, and beneath the Base, between the right and left Ventricle, two stones were found, whereof the one was as bigg as an Almond, the other, two Inches long and one broad, having three Auricles or crisped Angles: And in the Orifice of the right Ventricle, there was a fleshy fattish Matter.

4. That the whole Body was bloudless, thin, and emaciated, of a black and bluish Colour.

5. The Scull being opened, both the Cerebrum and Cerebellum were bigg in proportion to the Body; and out of it run much more Bloud, than was seen in both the other Regions together.

* * * * *

Of the designed Progress to be made in the Breeding of Silkworms, and the Making of Silk, in France.

The French King Henry the Fourth, having made a general Establishment all over France, of planting and propagating of Mulberry-trees, and Breeding of Silkworms, in order to set up and entertain a Silk-trade there; and having prospered so well in that Design, that in many parts of his Dominions great store of such Trees were raised, and Multitudes of Silk-works propagated, to the great benefit of the French people, forasmuch as it was a considerable beginning to avoid the transport of several Millions abroad for buying of Silks, and withall an excellent means of well-imploying abundance of poor Orphans and Widows, and many old, lame, and other indigent and helpless people; The present French King, hath lately revived and seconded that Undertaking by giving express order that it should be promoted by all possible means, and particularly in the Metropolis of that Kingdom, and round about it; and that for that end the whole way concerning that Work and {88} Trade should be fully and punctually communicated in Print; which hath also been executed by one Monsieur Isnard, in a Treatise published at Paris, in French, Intituled, Instructions for the Planting of White Mulberryes, the Breeding of Silkworms, and the Ordering of Silk in Paris, and the circumjacent Places, In which Book, the Method being represented, which that Great Prince Henry IV used in establishing the said Work and Trade, together with the success thereof, and the advantages thence derived to his Subjects, the Author, from his own Experience, and long Practice, delivers (and seems to do it candidly) all what belongs in this business in four main heads. First, he teaches the Means of sowing, planting, and raising White Mulberryes (as the Foundation of Silkworks) shewing how many several wayes that may be done. Secondly, The Breeding of Silkworms, the choosing of good Eggs, and their hatching, as also the Feeding of the Worms, and preserving them from sickness, and Curing them of it, together with the way of making them spin to best advantage. Thirdly, The manner of winding their Silk from their Bottoms, adding the Scheme of the Instrument serving for that purpose. Fourthly, The way of keeping Silkworms Eggs for the ensuing year.

Through the whole Book are scattered many not inconsiderable particulars, though perhaps known to most. The White Mulberry Tree, as it is in other qualities preferable to the Black, so this Author esteems it the best, not only for the durableness of the wood, and its large extent of usefulness in Carpentry and Joyners work; but also for the fitness of its leaves (besides their principal use for the food of Silkworms) to fatten Sheep, Goats, Cowes, and Hoggs, only by boyling and mingling them with Bran. The Berryes themselves he commends as very excellent to fatten Poultry, and to make them lay Eggs plentifully. In the Changes, Working, and Generation of this Insect, he is very curious to observe many things. Their Metamorphoses, as is known, are four, whereof the form of the one hath no conformity with any of the rest. The first from an Egge (of the bigness of a Mustard-seed, and of a darkish Gray Colour, when good) to a Worm or Caterpillar, but of a domestick, noble, and profitable kind, Black, when it first comes {89} forth, but growing white at last; having 24. feet, 8. on each side of the body, and 4. besides, close to each side of the head. During this form, they undergo constantly 4. Sicknesses, in which they cast their Skins, each sickness lasting about 4. days, wherein they feed not at all; but grow clearer, shorter, and thicker. The second from a Worm to an Aurelia or Chrysalis, having the shape of a small Plum, whereunto it is transformed after its spinning time is past; in which state it lies shut up, in hot Countries, for 14. or 15. dayes; in more temperate ones, 18. or 20. without any Food or Air, known to us. During which time this Insect leaves two Coats, both that of a Worm, whence 'tis changed into an Aurelia, and that of an Aurelia, whence it becomes a Papilio or Butterfly, in the Theca or Case. The third is, from an Aurelia to a Butterfly, coming out of the Theca with a head, leggs, and horns; for which passage it makes way by a whitish water, it casts upon the Silk, which moistning, and thereby in a manner putrefying it, the new creature thrusts out its head through the sharp end of the Case, by a Hole as big as its self. There is found no Excrement in the Case, but the two Skins only, just now mentioned.

Before they begin to spin, and about the latter end of their feeding, they must, saith the Author, be often changed, and have Air enough, by opening the Windows of the Room, they are in, if it be not too ill Weather; else, saith he, the Silk that is in their Belly, will cause so extraordinary a heat in them, that it burns their gutts, and sometimes bursts them; and the same (being a substance that resembleth Gum or Burgundy Pitch) will putrefy and turn into a yellowish matter.

He maketh the best marks of their maturity for spinning to be, when they begin to quit their white Colour, & their green and yellow Circles, and grow of the Colour of Flesh, especially upon the tail; having a kind of consistent softness shewing that they have something substantial in their Stomachs.