SCIENTIFIC AMERICAN SUPPLEMENT NO. 299

NEW YORK, SEPTEMBER 24, 1881

Scientific American Supplement. Vol. XII, No. 299.

Scientific American established 1845

Scientific American Supplement, $5 a year.

Scientific American and Supplement, $7 a year.



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TABLE OF CONTENTS.

I. ENGINEERING AND MECHANICS.—On the Progress and development of the Marine Engine.—Marine engines.—The marine boiler.—Steel boilers.—Corrosion of boilers.—How the marine engine may be improved.—Consumption of fuel.—Evaporative efficiency of marine locomotive boilers.—Screw propellers

Steam Ferry Boats of the Port of Marseilles.—2 figures.— Transverse and longitudinal sections

Opening of a New English Dock. 1 figure

Improved Grain Elevator. 1 figure

Improved Dredger. 1 figure.—Single bucket dipper dredger

Railway Alarm Whistle

Furnace for the Manufacture of Sulphide of Carbon. 1 figure

Brouardel's Dry Inscribing Manometer. 1 figure.—Gas indication of manometer

Centrifugal Apparatus for Casting Metals. 4 figures.—Centrifugal metal moulding apparatus

Apparatus for the Manufacture of Wood Pulp. 2 figures.—Dresel's wood pulp apparatus

Recent Progress of Industrial Science.—Presidential address, Convention of Mechanical Engineers

The Hoboken Drainage Problem

II. TECHNOLOGY AND CHEMISTRY—On some Recent Improvements in Lead Processes. By NORMAN C. COOKSON

Apparatus Used in Berlin for the Preparation of Gelatine Plates.— I. Mixing apparatus.—II. Digestive apparatus.—III. Triturating apparatus—IV. Washing apparatus—3 figures

How To Make Emulsions In Hot Weather. By A. L. HENDERSON

The Distillation and Rectification of Alcohols by the Rational Use of Low Temperatures. By RAOUL PICTET.—1 figure.—Pictet's apparatus for the rectification of alcohol by cold

The Removal of Noxious Vapors from Roasting Furnace Gases

New Gas Exhauster. 1 figure

Advance in the Price of Glycerine

Analysis of Oils or Mixtures of Oils Used for Lubricating Purposes

Nitrate of Amyl

III. ELECTRICITY, ETC.—The Electric Light in Earnock Colliery

Lightning and Telephone Wires

Conditions of Flames Under the Influence of Electricity

The Electric Stop-Motion in the Cotton Mill

Electrolytic Determinations and Separations. By ALEX, and M. A. VON REIS.—Determination of cobalt.—Nickel—Iron.—Zinc.— Manganese.—Bismuth.—Lead.—Copper.—Cadmium.—Tin.—Antimony.— Arsenic.—Separation of iron from manganese.—Iron from Aluminum

IV. MEDICINE, SURGERY, ETC.—Treatment of Acute Rheumatism. By ALFRED M. STILLE, M.D.

Method in Madness

Simple Methods to Staunch Accidental Hemorrhage. By EDWARD BORCK, M.D.—Bleeding from upper arm.—From arteries in the upper third of the arm.—From the thigh.—From the foot

Hot Water Compresses in Tetanus and Trismus

V. AGRICULTURE, ETC.—The Cultivation of Pyrethrum and Manufacture of Powder

Trials of String Sheaf Binders at Derby, England

The Culture of Strawberries.—Garden culture.—Field culture

Some Hardy Flowers for Midsummer

The Time Consuming Match

VI. ARCHITECTURE, ART, ETC.—Suggestions in Decorative Art. 1 figure.—Silver ewer by Odiot, Paris

Artists' Homes. No. l4.—Bent's Brook, Holmwood, Surrey, Eng.— 6 figures.—Perspective, elevations, and plans

VII. OBITUARY.—Achille Delesse, eminent as geologist and mineralogist

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ACHILLE DELESSE.

The death of this distinguished man must be recorded. An interesting resume of his labors by M. Daubree has appeared, from which we take the following facts. After a training in his native town at the Lyceum of Metz, which furnished so many scholars to the Polytechnic school, Delesse was admitted at the age of twenty to this school. In 1839 he left to enter the Corps des Mines. From the beginning of his career the student engineer applied himself with ardor to the sciences to which he was to devote his entire existence. The journeys which he undertook then, and continued later, in France, Germany, Poland, England, and Ireland, helped to confirm and develop the bent of his mind. He soon arrived at important scientific results, and was rewarded, in 1845, by having conferred to him by the university the course of mineralogy and geology in the Faculty at Besancon, where Delesse at the same time fulfilled the duties of engineer of mines. Five years later he returned to Paris, where he continued his university duties, at first as deputy of the course of geology at the Sorbonne, then as master of the conferences at the Superior Normal School. Besides this, he continued his profession of engineer of mines as inspector of the roads of Paris. The first original researches of the young savant concern pure mineralogy; he studied a certain number of species, of which the chemical nature was yet uncertain or altogether unknown, and his name was appended to one of the species which he defined. He studied also, and with success, the interesting modifications called pseudomorphism—the mode of association of minerals, as well as their magnetic properties. The attributes of a practical mineralogist aided him greatly in the culture of a branch of geology to which Delesse has rendered eminent services, in the recognition of rocks of igneous origin and of others allied to them. He studied in the field, as well as by investigations in the laboratory, for fifteen years, with an intelligent and indefatigable perseverance, and, aided by the results of hundreds of analyses, eruptive masses of the most varied kind, the knowledge derived from which threw light upon the principles of science, from granites and syenites to melaphyres and basalts. After thirty years of study and progress, other savants, without differing from him, progressed further in the intimate knowledge of rocks; but the historian of science will not forget that Delesse was the precursor of this order of research. His studies of metamorphism will long do him honor. The mineralogical modifications which the eruptive rocks have undergone in the mass are the permanent witnesses which attracted all his attention. The chemical comparison of the metamorphic with the normal rock pointed out distinctly the nature of the substances acquired or lost. One of the principal results of these analyses has been to lessen the importance attributed until then to heat alone, and to show in more than one case the intervention of thermal sources and of other emanations from below, to which the eruptive rocks have simply opened up tracks.

It is not only upon subjects relating to the history of rocks that Delesse has touched. Witness his work on the infiltration of water, as well as his volume relating to the materials of construction, published on the occasion of the Exhibition of 1855. The nature of the deposits which operate continually at the bottom of the sea offers points of interest which well repay the labor of the geologist. He finds there, indeed, a precious field to be compared with stratified deposits; for in spite of the enormous depth to which they form a part of continents, they are of analogous origin. Delesse laboriously studied the products of the innumerable soundings taken in most of the seas. He arranged the results in a work which has become classical with the beautiful atlas of submarine drawings which accompany it. Though he never slackened in his own especial work, he made much of the work of others. The "Revue des Progres de la Geologie," with which he enriched the "Annales des Mines" for twenty years, would have been sufficient to engross the time of a less active scientific man, and one less ready to grasp the opening of a discovery. This indefatigable theorist never neglected the applications of science: the nature and the changes of the layers which form the under earth; the course and the depth of the subterraneous sheets of water; the mineralogical composition of the earth's vegetation, were represented by him on several charts and plans drawn out in proper form. His maps which follow the route of many of the great French lines of railway explain the kind of soil upon which they are laid, and are of daily use. In the pursuit of his numerous scientific works, Delesse never failed in discharging his duties in the Corps des Mines. Having in 1864 quitted the service of the Government of Paris, which he had occupied for eighteen years, he was made professor of agriculture, of drainage, and irrigation, at the School of Mines, where he established instruction in these before being called to found the course of geology at the Agricultural Institution. Promoted to be Inspector-General of Mines in 1878, and charged with the division of the south east of France, he preserved to the end of his life these new duties, for which, to the regret of the School of Mines, he gave up his excellent lessons there. During the year of 1870 Delesse fulfilled his duties as a citizen, as engineer in preparation of cartridges in the department.

His nomination to the Academy of Sciences, which took place on the 6th of January, 1879, satisfied the ambition of his life. He was for two years President of the Central Commission of the Geographical Society; he was also President of the Geological Society. He was not long to enjoy the noble position acquired by his intelligence and his work. He suffered from a serious malady, which, however, did not weaken his intellect, and he continued from his bed of suffering to prepare the reports for the Council-General of Mines, and that which recently he addressed to the Academy on the occasion of his election. The greatness and the rectitude of mind of Delesse, his astounding power of work, his profound knowledge of science, his sympathetic sweetness, which were associated with sterling modesty and loyalty of character, made him esteemed and cherished throughout his whole career. He died on the 24th of March.—The Engineer.

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THE ELECTRIC LIGHT AT EARNOCK COLLIERY.

On the afternoon of August 9, Earnock Colliery, near Hamilton, belonging to Mr. John Watson, of Earnock, was the scene of an interesting ceremonial which may well be said to mark a new era in mining annals. In proceeding to win the rich mineral wealth of his estate, Mr. Watson determined that, in respect of fittings, machinery, and general appointments, it should be a model, and he has been highly successful in giving practical effect to his aims. Among other things, he early resolved to, if at all practicable, substitute the electric light for the ordinary mode of illuminating the workings, and after investigating the various systems, he decided on giving that of Mr. Swan a trial. Accordingly, since April last, Messrs. D. & E. Graham, electrical engineers, Glasgow, have been engaged fitting up the Swan incandescent lamp, with modifications, to adapt it for safe use in the mine, and on Tuesday the inauguration of the new light took place in presence of a large company of leading gentlemen from Glasgow, Hamilton, and the West. Arrived at the colliery about half-past one o'clock, the visitors were received by Mr. Watson, and after a brief space spent in inspecting the three magnificent winding and fan engines, the Guibal fan, and the framework for screening the coal, they were conducted by Mr. James Gilchrist, manager, down into the workings in the ell seam at a depth of 118 fathoms. Here at the pit bottom, in the roads and at the face, twenty-one Swan lamps were burning, giving forth a brilliant, steady flame, the luminosity of which, while sufficient to supply the desired light, had none of the disagreeable intensity associated with most systems of electric lighting. Besides the pear-shaped Swan lamp, in which the glowing or incandescence is carried on in vacuo, there is an outer lantern, the invention of Mr. David Graham, consisting of a strong glass globe, air-tight, protected with steel guards. Each lamp was also connected with two different forms of Graham's patent safety air tight contacts and switches for cutting off and letting on the current, the effect of which, it is believed, would be to render the lamps quite safe, even in the presence of explosive gas. At first the intention was to employ the fan-engine to drive the dynamo-electric machine or generator, but this was departed from, and an engine of 12 horse-power was erected in the workshops on the surface for the purpose. From the generator the electric cables, two in number, are conducted along the roof of the workshops over ordinary telegraph poles to the pit-head at No. 2 shaft, and thence down into the workings. From the ridge of the workshops to the pithead, a distance of several hundred yards, the cables consist of ordinary copper wire, three-eighths of an inch in diameter; inside the workshop and below ground, to allow of their safe handling, they are composed of insulated wires, while on the way down the shaft they are inclosed in a galvanized tube. Near the bottom of the shaft, branches are taken off to supply light to the principal roadways and to the haulage engine-room, the main cables being carried into one of the sections of the mine a distance of half-a-mile. After a careful inspection of the lamps at the pit bottom, the party were photographed in three groups, with the aid of the electric light, by Mr. Annan, of Glasgow, who may well be credited with the distinction of being the first to exercise his skill in the bowels of the earth. They were then led to the haulage engine-room and into the workings, where they witnessed the effects of the light. At the latter point, while, of course, the visitors were at a safe distance, a shot was fired, bringing down a large mass of coal. Having spent fully an hour below ground, the party returned to the surface.—Colliery Guardian.

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LIGHTNING AND TELEPHONE WIRES.

M. Bede, of Brussels, has an article in L'Ingenieur-Conseil on the above subject. He considers that a system of such wires forms the best and most complete security against lightning with which a town can be provided, because they protect not only the buildings in which they terminate, but also those over which they pass. At each end they communicate with the earth, and thus carry off safely any surplus of electricity with which they may become charged. It is, however, important that they should be provided with lightning conductors of their own, to carry off such surplus directly from the transmission wire to the earth wire, without allowing it to pass through the fine wires of the induction coils, which it might fuse.

Such lightning conductors usually consist of a toothed plate attached to one wire, close to another plate not toothed attached to the other wire. The copper even of such a conductor has been melted by the powerful current which it has carried away. In telephonic central offices, M. Bede has seen all the signals of one row of telephone wires fall at the same moment, proving that an electric discharge had fallen upon the wires, and been by them conveyed to earth.

This fact shows that wires, even without points, are capable of attracting the atmospheric electricity; but it must be remembered that there are two points at every join in the wire. M. Bede insists strongly upon the uselessness of terminating lightning conductors in wells, or even larger pieces of water. The experiments of MM. Becquerel and Pouillet proved that the resistance of water to the passage of electricity is one thousand million times greater than that of iron; consequently, if the current conveyed by a wire one square mm. thick were to be carried off by water without increased resistance, a surface of contact between the wire and the water of not less than 1,000 square meters must be established.

It is obvious that a wire let down into a well is simply useless. On the two-fluid theory, it offers no effectual way of escape to the terrestrial electricity; according to the older views, it would be absolutely dangerous, by attracting more electricity from the clouds than it could dispose of. The author advocates connecting lightning conductors with water or gas pipes, which have an immense surface of contact with the earth.

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CONDITION OF FLAMES UNDER THE INFLUENCE OF ELECTRICITY.

The experiments of the author have been principally directed to the alterations in shape and color produced in a flame when under the influence of positive or negative electricity. The flames were arranged so as to form one electrode of a frictional machine. When charged with positive electricity the flame became more blue, narrower, and pointed at the top, while little or nothing of the result was observed in negative flames.

A peculiar result is that the end of a negative flame returns to its own conductor, and that, according to the intensity of the electricity, and also depending on the width of the burner, this turning back of the flame is either intermittent or constant. Most noticeable are these results:

When the flame rises from a circular burner, or when burning round a metallic cylinder, in the latter case it returns to the metallic surface according to the intensity of electricity in an arc or angle, while the point of the flame divides into two branches, which separately perform more or less equal movements. If a body connected to the earth by a conducting wire is held opposite the flame at some distance, the flame will in all cases bend toward it; as the body is brought closer, the flame, if negative, will be repulsed, and, if positive, will be attracted, at least the upper luminous part of the flame, while the lower dark body of flame is also repulsed.

This phenomenon explains why a positive flame will burn through wire gauze, while a negative flame remains below the gauze. The positive flame becoming pointed explains the fact that this will drive a small fan wheel, while a negative flame will only just move it.

All these results are most prominently obtained with a pure gas flame, a stearine, wax, or tallow candle, very indifferently with a spirit flame, and least from a Bunsen flame rich in oxygen. They may not only be obtained with flames electrified direct, but also when placed under the influence of a long "Holtz" machine.

A flame placed between two small disks on the machine bends toward the negative pole, becomes widened, and, at a certain point of electric intensity, commences to vibrate and oscillate, exhibiting a peculiar stratification. Since these phenomena are also least observed in flames rich in oxygen, it appears to be a general law that carbon and hydrogen are more strongly attracted by the negative pole, while oxygen is more attracted by the positive pole, probably like in all polar differentially attractions, in consequence of a peculiar unipolar conductivity of the substances.

The return motion of the flame the author explains thus: The point of the flame loses more electricity by influence than it receives by conductivity. A paper strip fixed at one end to a large ball shows similar movements when its free end is pointed and made conductive. Why principally the negative flame returns may be explained in two ways—either the point of the flame loses much by radiation, or the base of the flame is a bad conductor. The former explanation would agree with the experiments made by Wiedemann and Ruhlmann, the latter with Erdman's theory of unipolar conductivity of flames. This theory is still further supported by the resistance on the negative electrodes noticed by Hittorf, which almost explains Erdman's experiments, because if negative electricity enters a flame with greater difficulty, then positive electricity must leave a flame with difficulty.—W. Holtz, in Wiedemanris Beiblaetter to Poggendorfs Annalen.

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THE ELECTRIC STOP-MOTION IN THE COTTON MILL.

The number of inventions for use as stop-motions in and about the various machines in the cotton mill has been to a certain extent something like the search after perpetual motion. Very available and quite satisfactory stop-motions have for a number of years been employed wherever the thread or sliver has been twisted so that strength was given it to resist a slight amount of friction, but the main trouble in the mill has been done after the sliver leaves the railway head and during its transit in the various processes employed between the railway head and the spinning frame or mule. Every carder or spinner knows that where an injury comes to the sliver because the sliver is soft, but partially condensed and very susceptible to injury, the injury is magnified and multiplied in every successive process. Virtually the field was long since abandoned for an accurate quick-working motion that should be applicable to any and all the machines and to every sliver or strand of the machine.

This invention was solved practically about two years since, and is now being employed as applied to drawing frames, doublers, speeder, intermediate, and slubber. It is a very cunning mechanical appliance, too, and has found favor to a great extent in England, where several thousand heads of drawing and speeders are already supplied.

This invention was exhibited at the Centennial in 1876, although in a somewhat crude state. Since that time it has been materially improved, and mechanically is very nearly perfect now. Many attempts have been made to apply a stop motion, which should be quick in its movement and accurate in its result, to carding engines or the card, not one of which, until the application of electricity, was worth the time spent in putting it on. With the electric motion, however, all this is changed, and the electric attachments are not of necessity so fragile as to be un-mechanical or to be not practical. The advantage has also been taken, in a mechanical way, of using cotton as one element, and, being non-conducting, so that no trouble shall arise from contact with the working parts of the electrical apparatus with the cotton itself.

To take into consideration all the possibilities that exist from the railway can to the front of the fine speeder is not needed by the practical reader, and would be useless to any other. The principle of this invention is the supplying of a magneto-electric current from a small magneto-electric machine attached to the card, speeder, or whatever machine it may be applied to which generates the current, and this machine is driven by a small belt from the main driving shaft. The machine in itself weighs but a few pounds, and can be driven by a half-inch or three quarter-inch belt, and requires a little more power than a light-running sewing machine.

One pole of the magneto-electric machine is connected by means of a rod or wire to the machine frame upon which it is to be used, and the other pole to the electromagnet in the ordinary way of conductivity of current, which means stretching the wire from one to the other. An armature is arranged so that when a thread is broken or a sliver or a strand of roving, the armature drops into a ratchet wheel; this ratchet wheel is made to revolve by the belt, and whenever it is impeded or stopped in its course it acts upon mechanism which throws the driving belt of the machine upon the loose pulley. Electrical contact is made by a very simple contrivance, and these attachments are only to act in the case of a breakage of a thread or strand.

As applied to a card, the calender rolls are both connected, one with the negative and one with the positive pole; when the sliver of cotton is between the calender rolls there is no connection, but if the sheet breaks down between the cone and the calender roll, the moment the calender rolls come in contact the electrical attachment operates and a stoppage ensues; and in the case, as with the American system, where a number of cards are used in a railway, this electric contact may be used for either one of two purposes-to stop the feeding of cotton into the card, or to ring a bell sharply and continue ringing it until the sliver is put between the calender rolls again and the card set to delivering cotton.

In drawing frames it may be attached so that, in the case of a breakage between the front roll and the calender roll, the electric machine acts; in the case of a lap upon one of the rolls or one end of the roll, or in case of breakage of the sliver at the back of the machine, in either case a stoppage would be instantly produced.

In being applied to the slubber a breakage either at the front or back can be arranged for. Upon intermediates the breakage of either one of the strands, if the machine was running two into one, from the creel to the roller, would cause the stoppage of the machine, or the breaking or tangling of ends between the front roll and the nose of the flier.

There are many other places where this motion can be applied. With mechanical means we require motion; with electricity we require simple contact of two differently arranged surfaces, and this can always be had by letting the cotton drop out from between the rollers; no radical changes are necessary, and we are glad to find that this electrical attachment is meeting with a very good success in England, France, and, so far, in the United States, and, undoubtedly, further and more extended opportunity will be found for this application.—Textile Record.

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ON THE PROGRESS AND DEVELOPMENT OF THE MARINE ENGINE.

[Footnote: A paper recently read before the Society of Mechanical Engineers by F.C.Marshall.]

The author began by referring to a paper read at the Liverpool meeting in 1872, by Mr. F. J. Bramwell, F.R.S., on "The Progress effected in Economy of Fuel in Steam Navigation, considered in Relation to Compound Cylinder Engines and High-pressure Steam;" then proceeded to continue the subject from the date of that meeting, to trace out whether any, and if so what, progress had been made; further, to consider whether or no we have reached the finality so strongly deprecated by Sir Frederick Bramwell in the discussion referred to, and, if not, then in what direction we are to look for further development.

From a table it would seem that the steam pressures are now much higher, the boilers have less heating surface, and the cylinders are much smaller for the indicated horsepower developed than in 1872; and at the same time the average consumption of fuel is reduced from 2.11 lb. to 1.828 lb., or by 13.38 per cent.

MARINE ENGINES.

The author then briefly described the modern marine engine and boiler. The three great types of compound engines may be placed as follows in the order of their general acceptance by the shipowning community: (1) The two-cylinder intermediate-receiver compound engine, having cranks at right angles. (2) The Woolf engine in the tandem form, having generally the high-pressure and low-pressure cylinders in line with each other, but occasionally alongside, and always communicating their power to one crank. Such a pair of engines is used sometimes singly, oftener two pairs together, working side by side to cranks at right angles; recently three pairs together, working to cranks placed 120 deg. apart. The system affords the opportunity of adding yet more engines to the same propeller to an indefinite extent. (3) The three cylinder intermediate-receiver compound engine, with one high and two low-pressure cylinders, the steam passing from the high-pressure cylinder into the receiver, and thence into the two low-pressure cylinders respectively. The cranks are placed at equal angles apart round the crank shaft, so as to balance the forces exerted upon the shaft.

These three types may be said to embrace all the engines now being manufactured in this country for the propulsion of steam vessels by the screw propeller. In their leading principles they also embrace nearly all paddle engines now being built, whether the cylinders be oscillating, fixed vertically, or inclined to the shaft.

The compound engine, in fact, in one of these three forms, may now be said to be universally adopted in this country; and the question of the relative value of simple expansion in one cylinder, and of compound expansion in two or more cylinders, which agitated the minds of some of our leading engineers ten years ago, is now practically solved in favor of the latter.

THE MARINE BOILER.

The marine boiler of to-day is in all its main features the same as it was ten years ago. The single-ended boiler, made with two, three, and sometimes four furnaces, is the simplest form, and for all powers under 500 indicated horse power is the most generally adopted. The double-ended form is largely used. It has been found more economically efficient than the single-ended form, by as much as ten per cent, in the writer's own experience. It is generally adopted for engines of large power, but for small power is inconvenient, owing to its occupying more room lengthwise in the vessel, and also involving two stokeholds and therefore more supervision. At one time great difficulty was found in keeping the bottoms of boilers of this kind tight. Owing to their length, the unequal expansion due to different temperatures at the top and bottom caused severe racking strains on the bottom seams and riveting—so severe in some cases as to rend the plating for a large part of the bottom circumference of the shell. This difficulty has now been to a large extent got over, in consequence of the greater attention given to the form and direction of the water spaces in the boiler itself, so as to induce circulation of water; the introduction of the feed-water at the top instead of near the bottom; the more careful management now usual on the part of engineers; and lastly, the use of larger plates, welded horizontal seams, drilled rivet holes, and more perfect workmanship throughout. A modification of double-ended boiler is that introduced by Mr. Alfred Holt. It has many decided advantages, but is costly to make. The formation of the two ends into separate fire-boxes leaves the bottom of the boiler free to adapt itself to the variations of temperature to which it is exposed. The separation of the furnaces from the combustion chamber, excepting through the opening afforded by a connecting tube, is an advantage in the same direction, and avoids almost entirely the racking strains due to irregular furnace action. The weight of water carried is less, and that of the boiler may also be made less; while the elliptical form of the two ends gives greater steam space.

A type of boiler largely used in her Majesty's Navy, somewhat like a locomotive boiler, is highly efficient in regard to weight and power developed. Many examples have yielded one indicated horse-power in the cylinders for every three square feet of heating surface, under natural draught and with a very moderate height of funnel; and this with a consumption of fuel not exceeding 21/2 lb. per indicated horse-power per hour under a working pressure of 60 lb. With the aid of a steam jet in the funnel, the heating surface per indicated horse-power has fallen below 21/2 square feet. The large water surface afforded for escape of steam secures almost entire freedom from priming, without the incumbrance of steam domes; and the large combustion chamber allows of the thorough combustion of the gases before their passage through the tubes. The locomotive type of boiler has lately occupied the writer's attention, with a view to its more definite introduction into marine work. The difficulties, however, which lie in the way of applying it to steamers going long voyages are very great. The principal difficulty lies in the necessity of burning a large quantity of fuel in a very limited space and time. This can only be done either by direct pressure or exhaust action applied at the furnace. In other words, we must either exhaust the funnel, which will absorb a large amount of power, but would be comparatively easy of application; or our stokers, as is the case with our miners, must work under a pressure of air.

STEEL BOILERS.

The writer stated that his experience in the manufacture and working of steel boilers was satisfactory. Many steel boilers of sizes varying from six feet diameter to fourteen feet six inches diameter have left the works at St. Peter's since 1877, when the first was made; and in no case has there been a failure of a plate after being put into a boiler, either in the process of manufacture or in working at sea. The mode of working is as follows: For shell plates, from five-eighths inch to seven-eighths inch thick, to warm each to a dark red heat before rolling, having previously drilled a few holes to template for bolting the strakes together; the longitudinal seams are usually lap joints treble riveted, requiring the corners to be thinned, which is done after rolling. The furnace plates are generally welded two plates in length, and flanged to form Adamson rings, and at the back end to meet the tube plate; the back flame-box plates are flanged, also the tube plates and front and back plates; and wherever work is put on to the plate it is annealed before going into the place. The rivet holes are drilled throughout. In the putting together the longitudinal seams of the thicker plates of the shells, great care is always taken to set the upper and under plates for the lap to their proper angle before they are bolted together, a point generally overlooked by the practical boilersmith.

CORROSION OF BOILERS.

The question of corrosion is one which is gradually being answered as time goes on; and so far very satisfactorily for steel. Some steel boilers were examined a few weeks ago which were among the first made; and the superintending engineer reports: "There is no sign of pitting or corrosion in any part of the boiler; the boilers are washed out very carefully every voyage, and very carefully examined, and I cannot trace anything either leaking or eating away. No zinc is used, only care in washing out, drying out, and managing the water." This is the evidence of an engineer with a large number of vessels in his charge. On the other hand, some of the most prominent Liverpool engineers always use zinc, and take care to apply it most strictly. The evidence of one of them is as follows: "We always fix slabs of zinc to most boilers, exposing not less than a surface of one square foot for every twenty indicated horse-power, and distributed throughout the boiler. This zinc we find to be in a state of oxide and crumbling away in about three months. We then renew the whole, and find this will last twelve months or more, when it is renewed again. Meanwhile we have no pitting and no corrosion; but on the contrary, the interior surfaces appear to have taken a coating of oxide of zinc all over, and we have no trouble with them."

HOW THE MARINE ENGINE MAY BE IMPROVED.

Then the writer considered our present marine engine as to its efficiency and capability of further improvement. The weight of machinery, water, and fuel carried for propelling ships has not had due attention in the general practice of engineers. By the best shipping authorities the writer is assured that every ton of dead weight capacity is worth on an average L10 per annum as earning freight. Assuming, therefore, the weight of the machinery and water of any ordinary vessel to be 300 tons, and that, by careful design and judicious use of materials, the engineer can reduce it by 100 tons, without increasing the cost of working, he makes the vessel worth L1,000 per annum more to her owners. That there is much room for improvement in this direction is shown by the following statement, giving, for various classes of ships, the average weight of machinery, including engines, boilers, water, and all fittings ready for sea, in pounds, per indicated horse power:

Lb. per I. H. P.

Merchant steamers.......................... 480 Royal Navy................................. 300 Engines specially designed for light draught vessels...................................280 Royal Navy, Polyphemus class (given by Mr. Wright).................................. 180 Modern locomotive.......................... 140 Torpedo vessels............................. 60

Ordinary marine boilers, including water... 196 Locomotive boilers, including water......... 60

The ordinary marine boiler, encumbered as it is by the regulations of the Board of Trade and of Lloyds' Committee, does not admit of much reduction in the weight of material or of water carried when working. The introduction of steel has reduced the weight by about one-tenth; but it will be the alteration of form to the locomotive, tubulous, or some other type, combined with some method of forced draught, to which we must look for such reductions in weight of material and water as will be of any great commercial value. The engine may be reduced in weight by reducing its size, and this can only be done by increasing the number of revolutions per minute.

It has hitherto been the practice to treat the propeller as dependent upon the size of engines, draught of water, and speed required. This process should be reversed. The propeller's diameter depends on the column of water behind necessary to overcome the resistance in front of it due to the properties of the vessel. This fixed, the speed will then fix the number of revolutions, which will be found much greater than is usual in practice, and from this the size of the engines and boilers will be determined. Great saving in weight can be effected by careful design and judicious selection and adaptation of materials, also by the substitution of trussed framing and a proper mode of securing the engine to the structure of the vessel, as worked out in H.M.S. Nelson, by Mr. A. C. Kirk, of Glasgow, and in the beautifully designed engines by Mr. Thornycroft, in place of the massive cast-iron bedplates and columns of the ordinary engines of commerce. The same may be said of the moving parts. In fine, the hull and engines should be as much as possible one structure; rigidity in one place and elasticity in others are the cause of most of the accidents so costly to the ship-owner; under such conditions mass and solidity cease to be virtues, and the sooner their place is taken by careful design, and the use of the smallest weight of material—of the very best kind for the purpose—consistent with thorough efficiency, the better for all concerned.

CONSUMPTION OF FUEL IN MARINE ENGINES.

Coming to the question of the consumption of fuel, a considerable saving has been effected in nine years, as shown in the following table:

Item. 1872. 1881.

Working pressure, lb. per sq. in......... 52.5 77.4 Heating surface per I. H. P., sq. ft.... 4.64 3.919 Piston speed, feet per min.............. 376 467 Coal burnt per I. H. P., lb.............. 2.11 1.828

This shows a saving equal to 13.38 per cent, in quantity of fuel consumed. Mr. Marshall then read a letter from Mr. Alfred Holt, of Liverpool, bearing on this subject, in which Mr. Holt spoke favorably of the single-crank engine, and stated his belief that the compound system would ere long be abandoned for the simple engine. He is endeavoring to feel his way to using the steam in one cylinder only, and so far the results have been encouraging, and he is now fitting a 2,200-ton vessel on that system. He is also endeavoring to do without a crank shaft, the forward end of the screw shaft carrying an ordinary crank with overhung pin. This experiment also promises satisfactorily. In his opinion the great improvement of the immediate future is to increase the steam production of our boilers. A ton weight of a locomotive boiler produces as much steam as six tons of an ordinary steamboat boiler.

Mr. Holt speaks of the coal account as one of the minor disbursements of a steamer. He does not give the ratio which coals bear to the total disbursements, but from other reliable sources Mr. Marshall found that, according to the direction of the voyage, it varies from 16 to 20 percent.—or, say, an average of 18 per cent.—of the total disbursements, in a vessel carrying a cargo of 2,500 tons. This will represent to-day about L3,000 per annum, and in 1872, at equal prices, the cost would have been L3,750—showing a saving of L750, equal to a dividend of, say, 3 per cent. on the value of the ship. Again, the cost of coal per mile run for such a vessel, in 1872, would have been at least 161/2d.; to-day it does not exceed 13d.

EVAPORATIVE EFFICIENCY OF MARINE BOILERS.

The marine boiler as now made is very efficient, but if the quantity of steam used be considered in relation to the increased pressure, it will be seen that the boiler of to-day is little if anymore efficient than that of ten years ago. The present boiler has an evaporative efficiency of about 75 per cent., and cannot be much improved so long as air is supplied to the furnace by the natural draught. To increase the efficiency from 75 to 82.5 per cent. would require about double the heating surface, the weight of boiler and water being also doubled, while the gain would be only 10 per cent. Mr. Blechynden's formula, used in Mr. Marshall's works for weights of cylindrical marine boilers of the ordinary type, and for pressures varying from 50 lb. to 150 lb., is as follows:

W = (P + 15) (S + D squared L) / C

or W = 2S (P + 15) / C

when S = D squared L, which is a common proportion.

Here W = weight in tons. P = working pressure as on gauge. S = heating surface, in square feet. D = diameter, in feet. L = length, in feet. C = a constant divisor, depending on the class of riveting, etc. For boilers to Lloyds' rules, and with iron shells having 75 per cent. strength of solid plate, C = 13,200.

This formula, if correct—and it is almost strictly so—would give the relative weight of boilers per sq. ft. of heating surface, for 105 lb. and 150 lb. total pressure, assuming we wish to increase the efficiency 10 per cent, as follows:

Weight at 105 lb. = 105 x 1 / C

Weight at 150 lb. = 150 x 1.75 / C = 263 / C

Hence the ratio of weight = 263 / 105 = 2.5

In other words, the boiler with the higher efficiency would weigh two and a half times that with the lower efficiency. In the case of a vessel of 3,000 tons, with engines and boilers of 1,500 indicated horse power, the introduction of locomotive boilers with forced draught would place at the disposal of the owner 150 tons of cargo space, representing L1,500 per annum in addition to the present earnings of such a vessel.

MARINE LOCOMOTIVE BOILERS.

Mr. Thornycroft has for some years used the locomotive form of boiler for his steam launches, working them under an air pressure—produced by a fan discharging into a close stokehold—of from 1 in. to 6 in. of water, as may be required. The experiments made gave an evaporation of 7.61 lb. of water from 1 lb. of coal at 212 deg. Fahr., with 2 in. of water pressure, and 6.41 lb. with 6 in. of pressure. These results are low, but it is to be remembered that the heating surface is necessarily small, in order to save weight, and the temperature of the funnel consequently high, ranging from 1,073 deg. at the first pressure, and 1,444 deg. at the 6 in. With the ordinary proportions of locomotive practice the efficiency can be made equal to the best marine boiler when working under the water pressure usual in locomotives, say from 3 in. to 4 in., including funnel draught.

It has fallen to the lot of the writer to fit three vessels recently with boilers worked under pressure in closed stokeholds. The results, even under unfavorable conditions, were very satisfactory. The pressure of air would be represented by 2 in. of water, and the indicated horse power given out by the engines was 2,800, as against 1,875 when working by natural draught, or exactly 50 per cent. gain in power developed.

Mr. Marshall then proceeded to refute the arguments which may be urged against the use of the locomotive boiler at sea, and which we need not reproduce. Coming to the engines, Mr. Marshall said that the total working pressure of to-day may be accepted as 105 lb., or equal to seven atmospheres. If it were boldly accepted that eleven atmospheres, or 165 lb., were to be the standard working pressure, the result would be a gain of 14.55 per cent., provided no counteracting influence came into play. Of course, there are forces which war against the attainment of the full extent of this advantage, viz., the greater condensation in the cylinders and loss in the receiver or passages.

In regard to the former, it may be questioned whether by steamjacketing the high pressure cylinder, correctly proportioning the steam passages, and giving a due amount of compression in both cylinders, this may not be reduced far below the generally received notion; and the latter cause of loss may be considerably reduced in its effect by a more carefully chosen cylinder ratio. The ratio usually adopted, between 3.5 and 4 to 1, whether the pressure be 70 lb. or 90 lb., may well be questioned. With a cylinder ratio of 2.95 to 1, the economic performance is very good, and equal to any with the higher ratio. A lower cylinder ratio has another advantage of considerable value, viz., that the working pressure can be much reduced as the boilers get older, while by giving a greater amount of steam the power may be maintained—at an extra cost of steam, of course, but not so great a cost as with higher ratios. The cut-off in the high-pressure cylinder usually takes place at about 0.6, and the ratio of expansion has decided the ratio of cylinders. The use of separate starting valves in both cylinders obviates that necessity.

The difficulties in the way of taking advantage of the higher economic properties of greater pressures than hitherto used on board ship, are, it is submitted, not insuperable, and it would be to the interest of all that they should be firmly and determinedly met. It may be accepted as an average result that the Woolf engine, as usually arranged, will use 10 per cent. more steam than the receiver engine for the same power.

Of the three-cylinder receiver type the data are insufficient to form a definite opinion upon; but so far the general working of the Arizona is stated to be as good, economically, as any of the two-cylinder receiver class. The surface condenser remains as it was ten years ago, with scarcely a detail altered. In most engines it remains a portion of the framing, and as such adds greatly to the weight of the engine.

It is a question seriously worth consideration whether or no the surface of tubes can be reduced. The practice at present is to make the surface one-half the boiler surface as a minimum, that is, equal to about 2 square feet per indicated horse power. In practice, the writer has found 1.4 square feet per indicated horse power to maintain a steady vacuum of 271/2 inches.

Mr. Marshall has just completed six pairs of engines for three twin screw ships, having steel shafts of 10 inches diameter, and has in each case run the engines at 120 revolutions per minute, while indicating 1,380 horse power from each pair for ten to fifteen hours without stopping; and in no case has a single bearing or crank pin warmed or had water applied, the surfaces on examination being perfect. In these engines all working bolts, pins, and rods, except the piston and connecting rods, are of steel, all rods in tension being loaded to 8,000 lb. per square inch. The boilers are of the Navy type, made throughout of Siemens-Martin steel plates, riveted with steel rivets, all holes drilled. Furnaces are welded and flanged; the tubes are of brass. In comparison with an ordinary merchant steamer's iron boilers of the double ended type, they weigh, including water and all appurtenances, as follows:

Double ended Type. Navy Type.

Weight, tons............ 135 ........... 146 I. H. P................. 1,400 .......... 2,760 Draught................ Natural ......... Forced.

SCREW PROPELLERS.

The screw propeller is still to a great extent an unsolved problem. We have no definite rule by which we can fix the most important factor of the whole, namely, the diameter. Mr. Froude has pointed out that by reducing the diameter, and thus the peripheral friction, we can increase the efficiency; and this is confirmed by cases—of Iris reduced 2 feet 3 inches, and the Arizona reduced 2 feet. This must, of course, be qualified by other considerations. The ship has by her form a definite resistance, and a certain speed is required; if the propeller be made too small in diameter, the ship will not be driven at the required speed, except at serious loss in other directions. This question was too large and complicated to be dealt with here, and should, in the first instance, be made the subject of careful and extended experiment, on which a separate paper should be written.

To sum up the whole. Progress has been made during the past nine years, and in the following particulars:

1. The power of the engines made and making show a great increase. 2. Speeds hitherto unattainable are now seen to be possible in vessels of all the various classes. 3. The consumption of fuel is reduced by 13.38 per cent. on the average; and numbers of vessels are now working on much less coal than that average, while the quality of the coal is in nearly all cases very inferior, so that it is not unfair to take credit for 20 per cent. reduction. 4. The working pressures of steam are much increased on the average, and are still increasing; many steamers now being built for 120 lb. per square inch, while 90 lb. is the standard pressure now required.

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STEAM FERRY BOATS OF THE PORT OF MARSEILLES.

The small steam ferry boats represented in the accompanying cut are doing service in the port of Marseilles, and the following description of them has been given by Mr. Flecher in the Bulletin de la Societe des Anciens Eleves d'Arts et Metiers:

All those who are acquainted with the Old Port of Marseilles know the inconvenience of communication between one shore and the other, and the high price of ferriage by row boats. To obviate this, Captain Advient has been struck with the happy idea of creating a cheap steam service (fare one cent), thus supplying a genuine want in the modes of locomotion of the city.

The building of these ferry boats, on a system providing for the use of separate hulls, was confided to Messrs. Stapfer, De Duclos & Co., of Marseilles, whose well-known reputation was a sufficient guarantee that the problem would be successfully solved.

There existed difficulties of two natures: The first of these related to the stability of boats such as this, having their engine, boiler, supply of coal, forty passengers who might all occupy one side of the vessel, a central superstructure, with roof; and, finally, all the weight centered on five feet of the deck, with nothing below to counterbalance it except the hollow hulls and two three-foot compartments, each placed toward the central portion of the hulls and designed as fresh-water reservoirs for the steam generator. The second difficulty was to obtain the best utilization possible of a screw placed in the current between the hulls and upon a shaft inclined toward the stern, that is, "stern" by analogy, for there is no distinction of fore and aft in ferry boats.



The conditions of the problem were finally fulfilled to the satisfaction of all concerned, and especially to that of the public.

The hulls, navicular in form and having a flat bottom, are constructed of one-tenth inch iron plate and 40x40 angle iron. Their dimensions are: Length, 33 feet; breadth, 31/4 feet; and depth, 5 feet. The internal distance between the two shells is 71/4 feet. These hulls, having absolutely water-tight decks, are connected below by tie bars of flat iron, and above by vertical stays 1 foot in length, which serve to support the floor-planks of the deck and boilerplate flooring of the engine-room. The engine-room, which is 191/2 feet long by 5 feet wide, is constructed of varnished pitch-pine, with movable side-shutters of teak. The roof, of thin iron plate, is provided with a ventilator to allow of the escape of hot air.

The passengers, to the number of forty or fifty, can move about freely from larboard to starboard, or from stem to stern, or seat themselves on the benches running along the inside of the guard railing on the two sides of the vessel. They are protected from rain by a roof, and from the rays of the sun by a curtain extending along the sides.

Although the usual method of landing is fore and aft, gangways have been provided at the sides for side-landing should it become necessary.

The general appearance of one of these boats may be likened to that of a floating street-car. Finally, a small apartment, provided with benches, is provided for the use of those passengers who might be taken sick, or for office purposes, if need be.

The total weight of one of the boats is divided up as follows:

Forty passengers................ 6,200 pounds, Engine and boiler............... 6,600 " Ballast, water, and equipment... 9,900 " Deck and superstructure......... 6,600 " Hull and accessories............12,500 " _

Total...........................41,800 "

or a displacement of about 700 cubic feet, corresponding to a maximum draught of 3.7 feet. The mean speed is 4 knots, or 41/2 miles per hour, a great velocity being unnecessary, owing to the small distance to cross in a port often obstructed by the general movement of vessels taking place therein.

The engine is from 16 to 18 horse-power. Its frame is inclined perpendicularly to the direction of the screw-shaft, the extremity of which is supported near the screw by a strengthened cross-stay serving as a pillow-block. The cylinder is 8 inches in diameter, and the piston has a stroke of 6 inches, causing the screw (which is 31/4 feet diameter) to make 200 revolutions per minute. The screw, although it has a wide surface of thrust, gives, nevertheless, a recoil of about 30 per cent., because of its location between the hulls and its oblique action on the shaft.

The steam is furnished by a tubular boiler having an internal fireplace and a heating surface of sixteen square meters, the draught being effected by the exhaust of the engine. This boiler, which is tested up to 14 pounds, is fed by a steam pump, or by a pump actuated by the engine. The feed pumps take water successively from one or the other of the reservoirs in the hulls. The reservoirs are filled in the morning, and their level is ascertained by two small and ingenious Decondun indicators, the dials of which are placed against the walls of the engine-room.

Taken altogether, these little boats are well arranged and quite handsome; and, since they were put into service in June, 1880, they have proved a great convenience to the hard-working and active population for which they were built.

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OPENING OF A NEW ENGLISH DOCK.

In July last, Admiral the Duke of Edinburgh, with the Naval Reserve Squadron under his command, arrived in the Firth of Forth and anchored in Leith Roads. His Royal Highness performed the ceremony of opening the new dock at Leith, which has been named after him. The "Edinburgh" Dock at Leith, which was commenced in 1874, consists of a center basin 500 ft. long and 650 ft. wide, and two basins 1,000 ft. long and 200 ft. wide, separated by a jetty having a width of 250 ft. The total amount of masonry in the wet docks is 100,000 cubic yards. The north and south quays are each 1,500 ft. long, and the two sides of the jetty 1,000 ft. long each, having a total quayage in connection with the dock of 6,775 ft. The walls are 15 ft. thick at the base, narrowing in two tiers to 8 ft. The new dock will cost altogether about L300,000. Leith now possesses five docks and a total quayage of three miles 808 yards, 1,234 yards of which is the old portion. These works have been constructed, at a cost of nearly one million sterling, by the Leith Dock Commissioners, whose chairman, Mr. James Currie, presented an address to the Duke of Edinburgh, on board the flag-ship H.M.S. Hercules, giving an account of their affairs. The other docks at Leith are named the "Old Dock," the "Queen's Dock," the "Victoria," the "Albert," and the "Prince of Wales Dock." The opening ceremony was arranged to consist of the steamer Berlin, with his Royal Highness and the Dock Commissioners on board, accompanied by Sir Donald Currie, M.P., and other gentlemen, passing through the entrance from the Albert Dock to the new dock, across which a blue ribbon had been stretched. At the moment when the ribbon snapped asunder, under the bow of the Berlin, the Duke of Edinburgh, stepping forward on the upper deck of the steamer, said, "I have now the gratification of declaring this dock open, and calling it the Edinburgh Dock." On this announcement being made, a signal was conveyed to a battery of guns, posted on the sea wall of the new dock, from which a party of the Royal Artillery fired a Royal salute. The steamer, having gone round the new dock, was brought up at the quay at the west. His Royal Highness the Duke of Edinburgh, with Prince Henry of Prussia, the officers of the fleet, and the Commissioners, disembarked and proceeded to the saloon in the new dock, where luncheon in honor of the occasion was given by the Leith Dock Commissioners.—Illustrated London News, Aug. 6.



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IMPROVED GRAIN ELEVATOR.

The illustration shows the apparatus at work transferring a cargo of grain from the hold of a ship by means of an elevating band fitted with buckets. By a simple contrivance shown in the engraving by diamond-shaped squares, the elevating band can be shortened or lengthened at pleasure, so as to suit it to the position the grain to be elevated occupies in the ship or barge. When the grain is elevated to the point whence it is to be transferred to the granary, railway truck, or other destination, the band travels horizontally on suitable bearings, the buckets being so constructed that in traveling they retain their load intact. The contrivance for lengthening and shortening the bucket band is an application of the "lazytongs" device, which is well known. The float of the elevator is shown at the left hand of the engraving, and, as seen in the latter, there is an automatic weighing machine, by which the material may be weighed as it is delivered, before it goes to the bottom of the elevator, to be again transferred by its means to the barge or granary. Simplicity, efficiency, and adaptability to any position in which elevators of this class are desirable, are the claims the patentees, Messrs. Behrns & Unruth, Lubeck, make for the advantages of their apparatus.—London Miller.



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IMPROVED DREDGER.

We illustrate below a useful type of dredger made by Messrs. Rennie, of Blackfriars, England. The drawing almost explains itself. The machine consists of a double barge or pontoon, in which is erected a derrick. This derrick works a "spoon" dredge at the end of a lever. The spoon, as shown, is at its lowest position. It will make a forward stroke, through about one-sixth of a revolution, and will thus become filled with mud and be lifted above the surface of the water. The motion will be imparted to it by the chain and pulleys seen at outer end of the derrick jib. The jib will then be swung round over the bank on a hopper barge and its contents delivered. The requisite power is supplied by the steam engine at the end of the pontoon. Messrs. Rennie have made several of these little dredgers, which are found very useful and handy in shallow water.—The Engineer.



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RAILWAY ALARM WHISTLE.

In order to prevent a train passing a danger signal during a fog or snowstorm without being seen by the engineer, the Southern Railway Company of France have attached to the locomotive a steam whistle, which is controlled by the signal. The whistle is connected with an insulated metallic brush placed under the engine. Between the rails there is a projecting contact bar, faced with copper, which is swept by the brush when the train passes. This contact piece is connected with the positive pole of a voltaic battery, the negative pole of which is in communication with a commutator on the signal post, from which a wire leads to the ground. When the signal is "line clear" the passage of the brush over the fixed contact produces no result; but when the signal marks "danger," the commutator brings the negative pole of the battery in direct communication with the ground, and when the brush passes over the contact the completion of the electric current causes the whistle to be sounded, so as to alarm the driver.—L'Ingen. Univ.

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FURNACE FOR THE MANUFACTURE OF SULPHIDE OF CARBON.

Sulphide of carbon (CS_2) is prepared by passing the vapors of sulphur over charcoal heated to redness. In laboratories, charcoal and roll brimstone are employed so as to obtain as pure a product as possible; but sulphide of carbon having now become so important a commercial product, and being employed for so large a number of industrial purposes, it has been found more economical to substitute coke for charcoal and pyrites for brimstone.

The Messrs. Labois, in their system of furnace represented herewith, have had in view the manufacture of this product under as economical conditions as possible, by coupling over two connected fireplaces the retort in which the pyrites is distilled, and that in which the reaction of the sulphur and carbon takes place.

The pyrites is fed from the hopper, A, into a distributing box, B, furnished with a valve which is maneuvered by a lever. From thence it descends into the retort, G, where it is roasted by the heat of the fireplace, L. The sulphur converted into a state of vapor passes through the conduit, R, into the coke or charcoal retort, G', which is divided into two parts by the partition, g g', of refractory clay, and heated by the fireplace, L'.



The conduit, R', leads the sulphide of carbon in a state of vapor to the condensing apparatus. The uncombined sulphur which is carried along is deposited in the first part of the retort by the arrangement of the partition, which permits of passage only below. The registers, V and V', permit of the introduction of the sulphur vapor and the exit of the sulphide of carbon being regulated.

The apparatus is so easy of installation that it may be applied without much expense to pyrites furnaces already in operation.

Wherever a manufactory of the product is to be started, the system recommends itself by its simplicity, and by the facility with which the operation may be watched and conducted.

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BROUARDEL'S DRY INSCRIBING MANOMETER.

Brouardel's manometer, represented herewith, is designed for showing graphically variations in the pressure of gas, either at the works during the course of manufacture, or at any point whatever in the system of piping.

For this purpose water manometers have hitherto been employed; but, although the indications given by these are very accurate, their form and weight are such as to render them not easily transportable; and then, again, considerable care is necessary in putting them in place.

Mr. Brouardel's registering manometer does not give so accurate indications, perhaps, but it possesses, as an offset, the merit of being very portable and easily put in place; and, besides, it inscribes the hour at which the pressure is exerted.

The apparatus consists of a metallic cylinder, A B, which carries a circular shoulder, C, that rests on a plate, D—the latter being put in motion by a clock which is wound up by means of a button under the base, E, of the apparatus. The two standards, F F, carry a crosspiece which supports a disk that closes freely the aperture of the drum, A B, in such a manner as not to impede its rotation.

In the interior of the cylinder there is a metallic cup which is connected with the central reservoir by an impermeable membrane, I. These three parts form a closed chamber, into which the pressure comes through a tube, F, provided with a cock. A spring, M, which counteracts the pressure, is arranged between the crosspiece, G, and the bottom of the reservoir. The latter carries also a small rod, K, which is provided with a cord made of braided silk. This cord runs over a pulley, N, whose axle carries at its other end a still larger pulley, O. Toward the middle of the latter is fixed a silken cord which hangs down on each side, after making several turns around the pulley. To the front cord is attached a slide, Q, moving in a vertical direction, and to which is fixed an inscribing style, R. The other extremity of the thread enters the hollow upright, and carries a weight which is greater than the combined weights of the slide, the membrane, and the internal reservoir. The upright serves as a guide to this counterpoise.

In order to use the apparatus there is affixed to the cylinder, A B, a sheet of paper divided in a vertical direction into as many parts as the cylinder takes hours to make one revolution. The divisions running horizontally represent centimeters of water or of mercury, according to the strength of the spring, M, which should be so constructed as to be in relation with the pressure. The operation of the apparatus may be readily understood.



When the gas reaches the pressure chamber, the spring, M, contracts, and consequently the counterpoise descends, and causes the cord, O, which carries the slide and writing style, to wind around the pulley. When the pressure diminishes, the movement takes place in an opposite direction.

The tracing is done by means of a special form of style giving indelible curves through the medium of colored glycerine. The position of the point is determined in such a way as to annul the friction of the pen, and consequently to give it greater sensitiveness.

It should be remarked that the course of the rod, K, is amplified in the tracing of the ordinates of the pressure according to the ratio of the diameters of the pulleys, N and O.

The apparatus may be carried by hand by means of the handle, S, either in or out of its case. To put it in operation, it is only necessary to connect the apparatus with a gas burner (located near the place where the variations of pressure are to be observed) by means of rubber tubing. The apparatus may be employed under the same circumstances as glass and U-shaped water manometers, with the further advantage that the results are registered, and consequently can be more easily compared.

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CENTRIFUGAL APPARATUS FOR CASTING METALS.

The apparatus represented in Figs. 1, 2, 3, and 4 is the invention of Messrs. Taylor & Wailes, and is designed for casting metallic objects in annular form, its arrangement being slightly varied according to the nature of the objects to be cast. In all cases where a special form is to be given to the outer or inner circumference of the object, or where it is desired to exert a pressure on the circumference, such form or pressure is obtained by the introduction of a core which may be expanded or contracted as need may be. For this purpose an expansible, metallic core is employed, the arrangement of which is shown in Figs. 1 and 2, and which is so fashioned that the inner circumference of the ring to be cast may receive the desired form. This core is formed of the pieces, g, g', made of cast-iron or any other material which fuses with difficulty, and which are placed in the revolving mould in such a way that after the cooling of the pieces the parts, g, recede by the shrinkage of the piece and thus free the core. The parts, g, of the core are in the shape of circular segments, and are united at their external circumference by a flange, along with which they form a shoulder piece for the casting. As a consequence of the rapid revolution of the mould, these parts are pressed by centrifugal force against the molten metal which is run into the mould.



The plan, Fig. 2, shows the arrangement of the parts, g, g', and allows it to be seen that the pieces, g', act as wedges against the segments, g, and push these out so as to form a perfect circle. The molten metal cannot become oxidized in the mould, since it is shut off from contact with the external air by the cap, C, which covers it. Oxidation may, however, be further prevented by passing some deoxidizing or neutral gas into the mould. For this purpose the mould is filled before the casting is done with some such gas as illuminating gas, carbonic acid, nitrogen, or hydrogen.

This improved process of casting may also be employed for objects which do not possess an exactly annular section. The moulds are then arranged eccentrically in a frame which is made to revolve rapidly during the cooling of the metal In this way the pieces are less strongly compressed at the places where they are nearest the center of rotation than a the points where the radius is greater.

Figs. 3 and 4 show section and plan of an apparatus of this kind. The sand moulds are arranged in the frame, a b which revolves about the axle, c. In the moulds there are iron cores, h, which press the metal during rotation and thereby produce compact pieces.

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APPARATUS FOR THE MANUFACTURE OF WOOD PULP.

For manufacturing wood pulp Mr. Dresel employs an apparatus such as represented in Figs. 1 and 2, consisting of an upright cylindrical reservoir, A, supported on a frame by means of trunnions, z. This reservoir, which is of boiler plate, is furnished with a cover, D, which has in its center a piece of tubing, with stop-cock, C. A series of tubes, R, whose diameter and length are proportioned to the volume of the boiler, A, is filled with the liquid which is contained in the boiler, so as always to be able to rapidly produce a pressure of nine atmospheres or more by direct heating. The flanges of the tubing are provided with a cut-off of angle iron identical with that of the tube, D. By means of this arrangement the cocks and the flanges, E, permit of communication between the serpentine tubing, R, and the boiler being interrupted; while the heat developed by the fire-place, F, causes an active circulation in both the tubing and boiler.



To put the apparatus in operation the cover, D, is first unscrewed, and there is put into the boiler a certain quantity of wood, which has been divided up by a cutting machine of special form. Then the boiler is filled to the proper height with the liquid necessary to dissolve the incrusting materials, the cocks, B, being closed. Afterwards there is fixed immediately beneath the angle-iron ring of the cover, D, a perforated iron plate upon which the contents of the boiler rest when the latter is turned up. Then the cover is fastened down and the boiler is put in communication with the heating apparatus. The cocks, E and B, are opened, so that the liquid may begin its movement in the tube, a, the boiler, A, and the tube, n. As soon as the proper temperature is reached for converting the wood into fiber and decomposing the incrusting matters, the heat is shut off in case the tubing, R, is not connected with another like boiler, and, after closing the cocks, E and B, and shut off communication between the tubing and the boiler, the latter is turned over and the cock, C, gradually opened in order to allow the steam to escape. When the temperature has descended to 100 deg. in the boiler the cover, D, may be opened, after the liquid has been allowed to flow out through the cock, C. Next, lixiviation is effected by connecting the cock, C, with the steam pipe, P, and causing steam under pressure to enter the boiler, A. The action of the steam on the contents of the latter, which are now converted into cellulose, mixed with a large quantity of dissolved matters and of liquid, effects a complete washing and permits of the recovery of considerable quantities of useful chemical products. Moreover, the steam purifies, decolorizes, and completely separates the fibers, and renders them more easily susceptible of being bleached. Finally, the perforated bottom, S (which is formed of two parts), is removed and the boiler emptied.

In order to have the operations under control, and for the purpose of safety, there is riveted into the boiler, A, a tube, T, containing a thermometer: and there is fixed to the tube, a, a pressure-gauge, M, and a safety-valve. The level of the liquid is ascertained by means of a gauge-cock, H.

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RECENT PROGRESS OF INDUSTRIAL SCIENCE.

The thirty-fourth annual summer meeting of the Institution of Mechanical Engineers began on Aug. 2, at Newcastle-on-Tyne. The following is an abstract from the address of the president, Mr. E. A. Cowper.

He began by stating that as members of the Institution of Mechanical Engineers, on revisiting their brother members and friends here in Newcastle, after an interval of twelve years, they came as it were to one of their natural homes; certainly to the home of one of the greatest engineers that England has ever produced, and the birthplace of the locomotive, which has done more than any other improvement, of our age to lessen the cost of materials to the men who have to use them, and therefore to cheapen and extend production in the most wonderful manner. He then went on to say that it seems but a few years ago since George Stephenson, at a meeting in 1847, proposed the resolution that the Institution of Mechanical Engineers be formed. He was strongly supported by a large number of the mechanical engineers of the country, and the speaker had the honor of seconding the resolution that he be first president. The intention was that engineers from all parts of the country should join to form a compact body capable of discussing and judging of all mechanical subjects and appliances. In this the institution had been eminently successful, and it numbered among its members mechanical engineers in every large town in the country, and has increased in strength and importance.

The last twelve years have been marked by many very important changes, while low prices have generally ruled. Among other causes of fluctuations in demand and supply (and consequently in values) must be mentioned the occurrence and the threatening of foreign wars, which disturbed the course of commerce greatly for some years. Such causes must be considered as extraneous to the sphere of influence possessed by good or bad manufacturing or engineering. Mr. Cowper does not look upon the very great expense of improved war material and implements as an unmixed evil for this country; for it so happens that we can better meet such outlay than any other nation, and thus our wealth gives rise to greater power and security than our neighbors possess; while, seeing that we are not an aggressive nation, such power tends materially at once to the progress of this country, and to the peace of the world. Having referred briefly to one cause of disturbance to the progress of mechanical engineering, he named another, which at the present moment is occupying thoughtful men to a considerable extent, namely, the arbitrary imposition of duties and bounties for the professed object of protecting manufactures, while in fact they constitute taxes on a nation for the benefit of a few individuals. In some countries excessive duties have been imposed, as against our manufactures, and it is even proposed to increase them; while in other cases bounties are actually paid out of the public purse to men engaged in a particular manufacture, on their exporting to this county certain of their wares, as, for instance, beet-root sugar.

One extremely significant lesson, resulting from high duties—which it may be hoped will not be thrown away upon the American public—is, that whereas our cousins on the other side of the water used to build almost all the American "liners" of wood, they now find that, with their excessive duties against the importation of iron and steel from England, they cannot compete with English iron and steel ship-builders and marine engineers. This is one of those damaging effects naturally produced by excessive protective duties; which, while they enable American ironmasters quickly to realize enormous fortunes, drive the American merchants to purchase English ships, or intrust their merchandise in English bottoms, as it is impossible to maintain protective duties at sea.

Whatever fluctuations have occurred, it is now pretty clear that several foreign nations have settled down to cultivate and extend their manufactures, and we are brought face to face with the fact—which has now been for some years growing to its present importance—that many articles which in years gone by we thought it to be our especial province to supply, are now produced in the very countries requiring them. Even Spain is awakening to the advantage of producing hematite iron from her own excellent ores, with English and Welsh coke carried out in the same ships that bring Spanish ores to this country.

Now with regard to the possibility of any foreign nation eclipsing us in our manufactures, he would say at once that any such successful rivalry on their part is far worse than the effect of any duties, even if they be prohibitive; for it means rivalry in the markets of the world, and possibly in our own markets here at home. Therefore it behooves us to put our house in order, and see in what way we may be enabled to manufacture better and with greater economy. Mechanical engineering is of such extreme importance in advancing civilization, that it is most essential that its progress should be rapid and unimpeded.

Perhaps the very large increase in steam shipping, and the change from sailing ships and paddle steamers to screw steamers, has been one of the greatest improvements of recent times, and it is none the less real or important from having been gradual, while the result to this neighborhood has been most beneficial. This change has been due in great measure to the introduction of very economical marine engines, chiefly of the compound type, together with better boilers carrying a higher pressure.

The speed and regularity of ocean steamers has also greatly improved, and one small scientific improvement has added much to the safety of traversing such seas as the Atlantic at a high speed—namely, the careful and continual use of a good thermometer, to ascertain constantly the temperature of the sea-water at the surface. For if an iceberg is floating within a quarter of a mile—or even half a mile, if the sea is pretty smooth—the surface water will be several degrees colder than the rest of the sea; since the very cold fresh water, resulting from the melting iceberg, floats on the top of the sea water for some distance.

No doubt the use of iron, and now of steel, has contributed most largely to the increase of shipbuilding in this country. Good arrangements of water ballast have also proved very useful; and steam cranes and arrangements for loading and discharging cargo have greatly promoted the use of steam colliers, enabling them to make more voyages in the year.

Closely connected with marine engineering is the great improvement in the economy of stationary engines, which has become more fully developed during recent years, both in reference to waterworks engines and factory engines. In aid of stationary engines, "surface evaporator condensers" have been found very useful, particularly where the supply of water is very limited; and at waterworks it is now very common to pass the whole water pumped through a surface condenser, thus giving a good vacuum without the expenditure of any water, and with the result of only raising the temperature of the water a very few degrees, on account of its large volume.

Locomotives have shared to some extent in the general improvement in machinery. The boilers are better made, and are safer at the higher pressures now carried than they were formerly with a low pressure. Several new valve gears of great promise have been brought forward, both for locomotives and marine engines. Among them Joy's motion should be again noticed. Mr. Webb says: "The engine shown at Barrow has been at continuous work ever since the Barrow meeting, and has run 30,278 miles; we had it in for examination on the 18th inst., and found the motion practically as good as the day it went out of the shop, more especially the slides, about which so many of the people who spoke at the meeting seemed to have doubts. I do not think you could get a visiting card between the slides and the blocks; in fact, the engine has been sent out to work again, having had nothing whatever done to it. The first thing, of course, that will require doing will be the tires; as far as I can see nothing else will want doing for some time."

A very fine engineering work has now been accomplished in America in reference to navigation, namely, the deepening of the channel at the mouth of the Mississippi through the training of the river by jetties and banks. In consequence, ships of large size may now go up the river—there being plenty of deep water above the mouth—and bring down grain cargoes, without the expense and inconvenience of transshipment, thus reducing the freight of corn to this country. This great improvement is the work of Captain Eads. A somewhat similar improvement was the blowing up of about 50,000 tons of rock from the bed of the river at the narrow pass of Hell Gate, near New York. It is to be hoped that these good examples may spur on our friends on the Continent to improve their harbors, so that large channel boats may cross with comfort to the passengers, thus avoiding the excessive expense that a tunnel would involve.

Great improvements have been made in the illumination of lighthouses by oil lamps; a light equal to 1,300 candles has been produced by Mr. Douglass, of the Trinity House, and now two such lights will be placed one above the other, where required. The electric light has made such numerous and rapid strides that it is impossible even to notice its various applications; but on the one hand the lighting by Dr. Siemens of four miles of dock frontage at the Albert Dock of the London and St. Katherine Dock Company, together with the railway behind the warehouses, and the warehouses and ships themselves, and, on the other hand, the elegant and steady domestic light of Mr. Swan, are excellent examples of the two extremes in this department. I believe we shall have the pleasure of closely observing the Swan light during our visit here. The lighthouse electric light is also a noble application of the great power of a single electric light on the arc principle. The most powerful electric light in the world is situated near here on the coast, between the Tyne and the Wear. It is possible, and even probable, that one of the great uses to which electric force will be applied eventually, will be simple conveyance of power by means of large wires; and as a higher percentage of power is gradually being realized, this method will become more economical. I may mention that 60 per cent. has already been obtained.

The invention of Messrs. Thomas & Gilchrist, by which a very large field of ironstone is now, for the first time, made available for the purpose of making good steel by the Bessemer process, bids fair to make very considerable alterations in the steel-making trade, and in the hands of Mr. E. Windsor Richards it has been made a great success, while in Germany there are several works also using the process largely. Mild steel is now being used to a great extent for the construction of steam boilers as well as of ships, and in steel castings for a variety of purposes, such as spur wheels, frames of portable engines, manhole door frames, etc., etc. Among the uses to which steel may be put is the manufacture of steel sleepers in place of wood. It is a very encouraging fact that there are now, or rather there were already, at Dusseldorf, in 1880, 70,000 tons of iron or steel railway sleepers in use in Germany. Mr. Webb, of Crewe, has exhibited a very promising arrangement of sleepers and fastenings, to be made either of iron or steel. Steel sleepers should also be used for tramways.

If, now, some clever ironmaster could only accomplish the task of making a good "street pavement" of cast iron, the increased demand for pig metal would be enormous. It has nearly been accomplished already, by several different modes of construction; and there are very many streets where the luxury of wood pavement, which wears very rapidly, cannot be afforded, and where macadamizing will not stand the wear and tear of the heavy traffic. The use of ingot steel, or very mild steel, for making tin-plates is now an established thing, and manufacturers are now taking this metal for making large tinned sheets up to seven by three feet.

The making of casks by machinery, cheaper and better than those made by hand, is now an accomplished fact by Mr. Ransome's machines. There are twelve factories already established abroad, some turning out 2,000 or 3,000 casks a week. This is a good case of English invention taking the lead in a manufacture.

Among good mechanical appliances that have been proved to be highly valuable to the civil engineer may be mentioned the excavating machine, which answers well for certain soils and situations, though not for all; and the dredger of Messrs. Bruce & Batho, for excavating from the inside of piers in water.

In manufacturing chemistry, which, with its numerous mechanical appliances, is much indebted to mechanical science and engineering, great advances have been made during the last dozen or twenty years. Aluminum has been brought into practical use to a large extent, it being at once a very light metal and a very cleanly one. "Anthracine," obtained from coal tar, has been manufactured largely for the purpose of producing the various brilliant dyes now so common.

New materials for making candles have been manufactured, in some cases by purely mechanical means, such as boiling together for some hours, at a pressure of several hundred pounds per square inch, neutral grease and water, when the water takes up the base, viz., glycerine, and leaves the grease as an acid grease. This same effect has been noticed in some steam boilers, where the same water, without admixture of fresh, has been used over and over again with surface condensers. Then, again, large rotating chemical furnaces have been introduced; and improved glass furnaces—particularly tank glass furnaces, in which the batch is put in at one end, and the working holes are toward the other end—have cheapened the actual production of glass, and are being worked largely on the Continent, and to some extent in this neighborhood. Toughened glass has made some progress for certain purposes. Besides the improved and extended use of glass in lighthouse illumination, it has again been pressed into our service for other purposes, through our greatly extended knowledge of the laws of optics.

Spectrum analysis has become of practical use, and photographs of the various Fraunhofer lines in the spectrum have been taken as permanent records of each experiment. That such extended knowledge should have been developed by that one little instrument, the lens, is but natural; for the lens is at once the means by which we discover the extreme magnitude of some portion of the infinite works of the Almighty in the architecture of the heavens, and by which we appreciate to some extent the extremely minute markings of a diatom that one cannot see with the naked eye. At the same time we feel sure that there are other markings still smaller, as every increase in the power of the microscope has always rendered visible some markings still smaller than the last; and in like manner has every increase in the power of the telescope developed more worlds and suns far away from our system and beyond our Milky Way. An approach to the infinite in minuteness and to the infinite in magnitude and distance is thus furnished to us by one instrument alone.

There was but one further observation that he would venture to make, and it is this.

When one looks back upon the goodly list of clever men and benefactors of the human race, who have lived, say, during the last hundred years, one is sometimes tempted to wish that more of those scientific men, who have had the most brilliant ideas, and been our greatest discoverers, should have striven to carry out their discoveries into practice. For instance, take Faraday's beautiful discoveries in electricity. It was, in a manner, left to Sir Francis Ronalds, Professor Daniell, Professor Wheatstone, Fothergill Cooke, Dr. Siemens, and others, to develop from those discoveries the "intelligence wires," and "bands," that now encircle the earth, and unite nations, and do so much to prevent misunderstandings.