GEOLOGICAL SOCIETY OF LONDON. partial nature of the security afforded by the pro- | sharp in outline, the objects losing their characterNov. 30, 1859.-Prof. John Phillips, Presi- posed plan, but lays stress on the fact that it istic appearance by over definition. dent, in the chair. Sir Walter James, Betshanger appears adapted to eliminate all the risks of the Park, Kent; George Dawes, Esq., Milton Iron-manufacture, except those which are inherent in works, near Barnsley, Yorkshire; the Rev. Julian the nature of the material operated on, and thereEdmund Woods,. Penola, South Australia; fore essentially incurable. Bassett Smith, Esq., 1 Elm Court, Temple; Captain Hickens, Bengal Engineers; Lionel Brough, Esq., one of H.M. Inspectors of Coalmines, Clifton; John Studdy Leigh, Esq., St. Stephen's Terrace, Bayswater; and John Pope Hennessy, Esq., M.P., were elected fellows. The following communications were read: 1. "On some Bronze Relics from an Auriferous Com Sand in Siberia." By T. W. Atkinson, Esq., F.G.S. 2. "On the Volcanic Country of Auckland, New Zealand." By Charles Heaphy, Esq. municated by the President. 3. "On the Geology of a part of South Australia." By T. Burr, Esq. From the Colonial Office. 1848. 4. "On some Tertiary deposits in South Australia." By the Rev. Julian Edmund Woods. Communicated by the President. MANCHESTER LITERARY AND PHILOSOPHICAL SOCIETY. Ordinary Meeting, Nov. 29th, 1859.-Dr. R. A. Smith, F.R.S., Vice-President, in the chair. A letter from Mr. Dyer was read relative to Mr. Jevon's paper. Mr. Dyer is led to conclude, from the facts which have been ascertained respecting the distribution of gold, that that metal forms a great part of the material of the earth's crust now in an incandescent state. Mr. F. O. Ward laid before the Society an instrument tèrmed a PSEUDO-DIASCOPE, and a paper setting forth its construction and use, and the principle it is designed to illustrate. By means of this instrument an aperture transmitting light is made to produce on one eye an isolated impression, while the other eye is directed to an opaque body, such as the hand held before it. The image of the aperture is then found to be transposed, and its perception ceases to be assigned to the eye by which it is really seen; the effect being that a perforation appears in the opaque body, through which the light seems to shine upon the eye by which this is viewed. The principle illustrated by this instrument, according to the author's view, is the essentially goniometrical and deductive nature of the visual act, whenever the distances of bodies are perceived, and their relative positions in space assigned. A Pseudo diascope was presented to the Society by the author, and the singular illusion produced by it was verified by the members present. Mr. F. O. Ward subsequently laid before the Society a plan of his for diminishing THE LIABILITY OF POWDER MILLS TO EXPLOSION, and referred to a correspondence between himself and Dr. Faraday on the subject. The plan in question consists in supplying to those portions of powder mills in which the powder is treated dry, an atmosphere incapable of supporting combustion-preferably carbonic acid gas-so as to obviate the danger of explosion so far as it arises from chances of ignition ab extra-as by the spark from a workman's pipe, of which an example was cited. The danger of explosions from the liberation of oxygen from the powder itself, by friction or otherwise, would of course remain; but this the author inclines to believe is a less frequent cause of explosion than ignition ab extra occasioned by the carelessness of workmen rendered indifferent to risk by long habit and emboldened by impunity. Dr. Faraday, in his comments on this plan, approves it as adapted to cut off one class of risks, and so to remove the point of danger further off, and also as not likely to deteriorate the quality of the powder immersed in the protective atmosphere. He points out, however, as a source of danger usually unsuspected, the possibility of the ignition of the gunpowder dust which collects on the beams of powder mills, and by which, he believes, explosions may be originated, as well as by the heating of the grains actually under trituration in the mill. Mr. Ward, in reply to Dr. Faraday, recognises the A paper entitled "SUPPLEMENTARY RESEARCHES IN THE HIGHER ALGEBRA," by James Cockle, M.A., F.R.A.S., was read by the Rev. A paper The author showed that what is called the total heat of steam, or the quantity liberated when steam is condensed into water of 0° centigrade, consists of, 1st, the true heat of evaporation; 2nd, the heat due to the work done on the steam during the condensation; and, 3rd, the heat liberated by cooling the water from the temperature of condensation to the freezing point. The made the object of a very careful and elaborate determination of the total heat of steam had been research by Regnault, but it appeared to the author that independent experiments conducted in a different and more direct manner would not be without interest. The following is a summary of the results obtained by him compared with those of Regnault: :1 A paper was also read by Dr. Joule, entitled "ON A METHOD OF TESTING THE STRENGTH OF STEAM BOILERS." The author adverted to the means hitherto adopted for testing boilers. 1st. That by steam pressure, which gives no certain indication whether strain has not taken place under its influence, so that a boiler tested may subsequently explode when worked at the same or even a somewhat less degree of pressure. He trusted that this highly reprehensible practice had been wholly abandoned. 2nd. That by hydraulic pressure obtained by a force pump, which does not afford an absolutely reliable proof that the boiler has passed the ordeal without injury, and moreover requires a special apparatus. The plan which had been adopted by the author for two years past with perfect success was free from the objections which applied to the above, and is as follows:-The boiler is entirely filled with water. Then a brisk fire is made in or under it. When the water has thereby been warmed a little, say to 70° or 90° Fahrenheit, the safety valve is loaded to the pressure up to which the boiler is to be tested. Bourdon's or other pressure indicator is then constantly observed; and if the pressure, occasioned by the expansion of the water, increases continuously up to the testing pressure without sudden stoppage or diminution, it may be safely inferred that the boiler has stood it without strain or incipient rupture. In the trials made by the author, the pressure rose from zero to 62 lbs. on the square inch in five minutes. The facility of proving a boiler by this method was so great that he trusted that owners would be induced to make those periodical tests, without which fatal experience had shown that no boiler should be trusted. Microscopical Section, Nov. 21st, 1859.-Messrs. J. Lynde and A. Brothers exhibited the process of photographing microscopic objects as used by them, and which, from the specimens produced, appears very excellent. Mr. Parry described a simple form of camera which he had used, and in which he dispensed altogether with the use of the microscopic body, simply inserting the object glass into the lens aperture, and fixing a suitable stage to support the object. Messrs. Lynde and Brothers stated their intention of attempting to photograph thicker and more opaque objects; and Mr. E. W. Binney promised to supply them with sections of fossil woods, which he said had been drawn by artists, but with poor success, as the tendency of draughtsmen was to make them too ASSOCIATION OF FOREMAN ENGINEERS. The ordinary monthly meeting of the Association of Foremen Engineers took place at their rooms in the City of London on Saturday night last, and was very numerously attended, notwithstanding the inclemency of the weather, and the fact that its members are located-many of them-at considerassembly. The minutes of the November meeting able distances from their very central place of were first read and confirmed, several elections followed, and after the reading of a letter from Colonel Dixon, of Enfield Lock, expressive of his high regard for the Association, and his regret at not being able to attend this particular meeting, Mr. C. F. Hayes proceeded with his concluding paper on the manufacture of the Enfield rifle. He said that he had on previous occasions endeavoured to explain the mode of preparing the Enfield rifle and of the bayonet, and that he had various components and furniture of the long James now arrived at the lock and stock of the weapon. Upon the table lay the various parts of a rifle lock in the forged and finished stages, and a walnutwood stock, as it left the machines which had shaped, mortised, drilled, and grooved it. These, together with some of the standard gauges used at the small-arms factory, and some exquisite photographs of the various machines at that place, assisted Mr. Hayes materially in his explanations. The hammer was the first item alluded to; this was of wrought-iron roughly forged by hand, and then struck by force of a Nasmyth steam drop into a pair of dies; afterwards it was annealed and forced through a cutting-press, which removed the superfluous metal squeezed out between the forging dies. A series of operations followed amounting in all to twenty-six, and in each of which great care had to be observed. The lockplate was of wrought-iron. It was brought nearly to its proper form in a rider forging machine, and then struck at a welding heat into a die. Next, eight holes were drilled through it for the purpose of attaching to it the various pins, springs, &c., which go to make the lock complete. Gunner, Esq., had greatly improved the apparatus used in shaping and finishing the lock-plate, and he very deservedly filled the post of inspector of small arms at Enfield. Very soon the lock-plate would be finished from the anvil without the intervention of hand labour at all. After casehardening, the plate is tested by standard gauges, to be assured that there is no distortion, and, if found perfect, is ready for "assembling," that is, for being united with its fellow-portions of the rifle. The tumbler was a very important part of the lock, and was made of cast-steel. Much attention was requisite on the part of the workers in dealing with this, lest the heats taken upon it should alter and deteriorate the character of the metal used. Improved copying machines were now employed in the completion of this portion of the weapon, and after a variety of minor but yet consequential processes, it was finally hardened and tempered. Mr. Hayes here explained that the labour-saving machines invented by himself, and pertaining principally to the construction of the several parts of the lock, had saved from two to four thousand pounds per annum to the country-a rather important announcement. The sear and the sear spring were next referred to, and the manipulations necessary for their perfecting-minute and numerous-were explained with an elaborateness of detail which prevents our following the reader of the paper through his account of them. Finally, the sear spring is tested by pressure in a Salter's spring, and if found satisfactory, passed for service. The swivel is a small affair, but of some moment to the action of the lock. It is cut from a bar of 5-16th square steel, and after being milled, and faced, and drilled, and hardened, and tempered, it takes its place as a finished article. The bridle governs the movement of the lock, and is of great consequence, therefore, to the rifle. It is of wrought-iron got up by stamping, and milling, and cutting, and trimming, which, aided by some excellent gauges devised by Mr. Barnes, enables the workman to turn it out of hand expeditiously and well. The main-spring was of the best cast-steel, and it was needless to say, observed Mr. Hayes, that the skilled workman must exercise his utmost skill and judgment in dealing with it. This brought the reader of the paper to the manufacture of the stock of the rifle, which was of walnut wood-a material imported largely from Lombardy for this particular work. Copying machines, the idea of which was no doubt gained originally from Mr. Blanchard's lathes for turning irregular figures in wood, such as boot trees, &c., &c., were the principal media employed in converting a roughly sawn piece of walnut tree into a handsome and mathematically true-shaped bearer of the barrel, lock, and other fitments of the rifle musket. Space forbids our going minutely, as Mr. Hayes did, into the action of the shaping and cutting machines used in the preparation of stocks for muskets; we can only say that they do their work with nnerring accuracy, and that there is no chance of any portion of the steel, iron, or brass attachments misfitting their places after the machines have done their offices. The interesting paper was brought to a conclusion by a summary of the number of operations performed in the perfecting of a rifle musket being given, and these amount in all to 769! A vote of thanks, proposed by Mr. W. Keyte, seconded by Mr. Briggs, and strongly advocated by the President, Mr. Joseph Newton, of the Royal Mint, was next given to Mr. Hayes, who expressed his acknowledgement of the honour conferred. The announcement of a paper for the January meeting-Saturday the 7th proximo-by Mr. Beckley, on "The Instruments used at the Royal Observatory, Kew," closed the proceedings. MEETINGS FOR THE ENSUING WEEK. Punjaub, communicated by Sir Chas. Wood, India Districts bordering on the Thomson, Frazer, and Harrison Rivers," by Licuts. Mayne, R.N., and TUES.-Inst. Civil Engineers, Annual General Meeting, at 8 p.m. WED.-London Inst., "On the Physical History, Structure, Society of Arts, "On the Great Eastern," by Mr. Royal Geological Society, I., "On some Bones of Polytychodon, from the Chalk of Dorking," by Prof. Owen, F.G.S.: II., "On some new Reptilian Remains, with Shells of Pupa and an Iulus from the Coal-measures of Nova Scotia," by Dr. Dawson, F.G.S.; III., "On some Fossils from Bahia,' by S. Allport, Esq.; IV., "On some Cheirotherian Tracks in the Upper Keuper of Warwickshire," by the Rev. P. B. Brodie, F.G.S. THU.-Royal Society, at 8 p.m. FRI.-London Inst., "On Certain Principles of Vegetable and Animal Chemistry," by S. A. Malone, Esq., F.C.S., at 7 p.m. Law Cases. WILD'S PATENT FISHES FOR RAILWAY JOINTS. COURT OF QUEEN'S BENCH, DEC. 3.-(Sitting at HARWOOD AND OTHERS v. THE GREAT NORTHERN Mr. Knowles, Q.C., Mr. Grove, Q.C., Mr. Hindmarch, and Mr. Webster appeared for the plaintiffs; and Mr. Bovill, QC., Mr. C. Pollock, and Mr. Horace Lloyd for the defendants. The trial of this cause, which has occupied the Court three days, was this day brought to a close. The plaintiffs were the executors of the late Charles Heard Wild, and they sued the Great Northern Railway Company to recover damages for the infringement of a patent granted to Mr. The jury found their verdict for the plaintiffs CROSSLEY'S PATENT JACQUARD MACHINERY FOR WEAVING CARPETS. COURT OF QUEEN'S BENCH, DEC. 5--(Sitting at Nisi Prius before Lord Chief Justice Cockburn and a special Jury.) CROSSLEY AND OTHERS, TALBOT. Mr. Atherton, Mr. Grove, Mr. M. Smith and Mr. Webster appeared for the plaintiffs; Mr. Knowles, Mr. Hindmarch, and Mr. Thruff for the defendant. The action resulted in a verdict for the plaintiff (without the case being gone into at length) with the damages (£2000) in the declaration subject to a reference. PRESS'S IMPROVED QUICK ACTION Provisionally Registered June 30th, 1859. THIS improved drill stock will drill holes in metals and other substances with greater ease and rapidity than is attainable by the use of any description of drill stock hitherto made; so, at least, says the inventor of it. Wild on the 16th of March, 1853, for improve- | rosion," by using a mixture, before applying strengthening, and also for keeping in place bolt The Lord Chief Justice said that would be a In the drawing AA, A' A' is the frame of the thence around the spiral threads, where its ends BLACKBURN'S PATENT TRACTION THE Smithfield Club Cattle Show and Implement Verdict for the plaintiffs accordingly. STEAM-PACKET COMPANY. Mr. Serjeant Petersdorff and Mr. Webster peared for the plaintiffs, and Mr. Wilde and Murray for the defendants. This case (involving a question whether Messrs. Miller, of Glasgow, had infringed "Westwood's patent for protecting the iron of ships against cor Fig. 1 of the accompanying engravings is a side elevation, and Fig. 2 is a plan of a locomotive or traction engine constructed according to Messrs. Blackburn's invention. A 4 is the large travelling drum, which is connected to trunnions A' A' by means of arms or spokes B B meeting in cen-L L of the engines;. M M are the piston-rods, which are jointed to the cranks N N that drive plied with water through the trunnion 4", opposite to that which supplies the cylinders with steam; Z is a water-tank which receives the steam from the exhaust, and contains a supply of water for the boiler; Z' is a coupling chain for connecting implements of culture or other apparatuses to the engine. As an implement of culture the patentees employ a cylinder fitted with scarifying or digging tines, which cylinder is fitted to the afterpart of the engine, and is caused to revolve by teeth formed on or attached to its sides, into which teeth pinions gear, receiving motion from the travelling drum of the engine. The depth at which the tines work in the ground can be regulated at will, and arrangements are provided for raising the cylinder wholly out of the ground. Tasmania has been successfully submerged, and Ο Ν Ꮋ Ꭼ Ꭺ Ꭲ . cherry took only thirty minutes to melt. Larger masses of snow (if round) take far longer, because the heat of the external air cannot come in PROVE THAT THE HEAT WHICH DR. BLACK contact with the centre portions. DISCOVERED TO BE ABSORBED DURING THE LIQUEFACTION OF ICE, AND WHICH HE CALLED LATENT HEAT, IS NEVER GIVEN OUT AGAIN ON THE FREEZING OF WATER, WITH REMARKS ON A PECULIAR PROPERTY WHICH SEEMS TO BE By HORATIO PRATER, Esq. I HAVE repeated the experiment three times of mixing two parts by measure of snow and one part of water at 172° F., and I never found the thermometer fell lower than 36 (even when I diminished this water to a part), and before it fell thus low twelve minutes had elapsed, and the snow was then only just melted. The almost sudden fall to 32° F. which some experimentalists speak of to prove a loss of 140° in this experiment, doubtless arises from the difficulty there is to prevent the actual contact of snow or ice with the bulb of the thermometer. To prevent this I tied two folds of fine linen round it; and even then we must remember that a stream of very cold water will be apt sooner or later to flow directly on it, since the snow is constantly moving in the water. However, in my experiments the whole bulk of the water certainly (sooner or later, according to the temperature of the room) fell to 36°, and as the temperature of the room was as high as 58°, this may probably be the reasonallowing for difference in thermometers, and adding, perhaps, the fact that I used snow and not ice-why it never fell to 32, as in Dr. Black's experiments. He took equal weights of water and ice, but as I found snow thaws into between ths and ths its bulk of water, I took an overweight of snow. I found the very sudden fall to be to about 44°; in seven minutes more it stood at 38, at which time the snow was not quite melted; and in ten minutes more at 36°, when the snow was only just melted. The long time (viz., on an average twenty minutes) that snow in the above proportion took to melt in water at 172, is worthy of remark, and proves Thomson's statement (On Heat, p. 163), that "snow instantly melts" in such circumstances, to be erroneous.* When I mixed equal bulks of water at 32° and at 172°, the point to which the thermometer came suddenly was 110°; it then continued to sink, but very gradually, for even after 45 min. it stood at 70°, the room being 58° as in the former experiments. When I took two bulks of this ice water and one of water at 172°, in three minutes it stood at 78, and then very gradually (viz., in four minutes) fell to 76°, and in eight minutes more to 70°, and there remained, as in the former experiment, a long time. These experiments sufficiently confirm Dr. Black's great discovery, viz., that an equal proportion of ice, or snow, mixed with water at 172 makes the thermometer fall far lower than when mixed with water at 32. That in my experiments it never fell below 36° is a difference too light to merit attention. I found that snow water at 32° took 57 minutes to gain 12 of heat, and still continued to rise very slowly, the temperature of the air being 48°. In 34 minutes it rose from 32° to 36, in 23 minutes more (total 57 minutes) to 41°, and did not rise to 46° for nearly two hours. The very slow rise of the thermometer depended on the external air being only 48°, but the same quantity of snow would doubtless have taken very far longer to melt and rise at the same point; though at the same temperature I observed that a piece of snow of about the size of a small Professor Thomson often speaks of the slowness with which ice melts, and attributes it to the necessity for absorbing 140°, but I believe the real cause to be (and this cause applies equally to the slow melting of snow in water at 172) that heat has not merely to be absorbed, but the COHESION of the ice or snow has also to be overcome, for we know that ice can't remain ice, and absorb heat above 32. If it could, these 140 could be absorbed as quickly in this case as in many others. In confirmation of Black's theory of the great degree of heat absorbed by the liquifaction of ice, may also state that when I mixed intimately two tea-spoonfuls of snow with one ditto of muriate of soda, the temperature very soon sunk to 4°, (an experiment well known-Thomson, p. 169, says it sinks to 5°.) But in 45 minutes it rose again to 38°. Although in this experiment nearly 3rd of the mass remains solid as muriate of soda, yet enough liquid is produced rapidly in order to produce cold of 4 below zero, and hence Thomson (op. cit. p. 172) says, "snow and chloride of calcium which liquify immediately on mixture, produce a much greater cold (viz., from +32° to -50°,) than snow and salt, which liquify very slowly." "Very slowly," perhaps, when taken and compared with chloride of calcium, but taken by themselves I thought they liquified quickly. While I admit, therefore, that Thomson's explanation is right as regards the main point (viz., rapidity of liquifaction), I am inclined to think that other causes also assist in causing so vast an increase of cold in one of these cases beyond the other.* That sudden liquefaction is the main cause is, however, shown by mixing a teaspoonful of snow water at 32° and one of salt, when I found the thermometer remained without falling at all, and was not long in rising even to 36°; the temperature of the air in these experiments being, as above, 48- -a point to be attended to, says Thomson (note p. 168). I am inclined to draw the following inference (in addition to Black's inference) from this experiment with snow water at 32°, which I believe has never been tried before. This inference is, that some of the effect depends not only on rapid liquefaction (strictly so called), but also on the sudden production of a nisus, or power of resistance, from the, so to call it, unnatural state in which snow is thrown when mixed with salt or chloride of calcium, and also in the former experiments when mixed with water at 172. Even Thomson himself has unconsciously introduced a physiological cause, in addition to Black's mere mechanical theory of 140, into this discussion, when he is obliged to admit RAPIDITY OF ACTION Counts for so much; for it makes one 140° more than another 140° when the action is quicker. that it does not act. solely in the mechanical way supposed by Thomson is proved, I think, by the cold produced in many of these cases being far greater than is necessary to form ice. In many of these cases there is clearly a production of cold far beyond what this latent heat theory of 110° can account for, and that, too, when no snow or ice at all is used; for when phosphate of soda, nitrate of ammonia, and diluted nitric acid are used (proportions, 9, 6, 4) a cold of 71° is produced within a few degrees of that produced by snow and muriate of lime. Now, here is cold produced far greater that when water gives out, according to the prevailing theory, its 140° and becomes snow and ice, and that, too, without any assistance from snow or ice! A point worthy of remark is that the cold produced is very transient. Thus, in my experiment with snow and salt, I think it may be said to have lasted only while liquefaction and the peculiar motion accompanying this was going on, for in 45 minutes the thermometer rose actually as high as 48. The secret of the production of cold, even in this case far beyond what the absorption of 140” can account for, is, I believe, to be ascribed to the NATURAL action of liquefaction being interfered with, and to its being MUCH HURRIED by the addition of the salt.* In the great proportion of frigorific mixtures two crystallised soluble salts are used; but that chemical affinity is little concerned in the effect is shown by the solution of one salt only in simple water producing much cold. Thus, for instance, nitrate of ammonia and water lowers temperature from + 50° to +4°. (Thomson, p. 168.) Now, I infer from this fact, and others above quoted, that the supposed conversion to water of the solid water of crystallisation and the necessary absorp tion of 140, does not explain the production of this very great degree of cold, and consequently I infer that this is produced by the RAPID SEPARATION of the atoms of matter by solution. In this way heat is absorbed, and consequently cold produced by the nisus of the atoms of matter to REGAIN the quantity of heat by which they are naturally surrounded or with which they are combined. That this is the true theory seems to me to follow from reflecting that the COMPRESSING of homogeneous atoms together (as in the compression of air) produces heat; as also of heterogeneous atoms by the action of chemical affinity; thus when oxyde of zinc, &c., is formed by the action of dilute sulphuric Again, is not the production of cold in this case acid, or when iron wire burns in oxygen gas and (though in others of heat) in overcoming THE CO-produces the oxyde. Thus, compression and cheHESION of ice entirely overlooked in Black's mical affinity act in the same way in regard to theory? Is not this cold produced on the spot- their tendency to force the atoms closer together. "then and there"-by this struggle of ice to (To be continued). retain unmolested its state of ice? Accordingly when water at 32° is substituted, we find (strange to say) that no cold whatever is produced-clear proof that at least, in the case of salt, Thomson's theory of the solid water of crystallisation absorb. ing 140° in order to become water (and thus causing cold) does not hold. He gives (p. 172) this as the theory for the production of a cold of 49.5° (viz., from 545° to 5°) when 500 grains sulphuric acid are mixed with 333 grains water, the mixture allowed to cool, and then 10-40 grains of crystallised sulphate soda finely powdered put in. Again, says he, "Chloride of calcium in crystals con tains more than half its weight of solid water," in reference to the cold of 82° produced when this salt is mixed with snow. Now, in reference to these experiments of Bischof and Walker, who assert the cold is not produced except the salts contain their water of crystallisation, we are hence clearly obliged to admit that this is concerned in the effect; but The reason why the thermometer falls to-4° or-5' in this experiment, and when ice is simply melting remains at 322, is no doubt to be ascribed to an excess of cold produced above the 140' which Black rightly inferred do not affect the thermometer, because they combine with the water formed. But in the snow and salt experiment not only are the 140° absorbed, but as they also must be insensible to the thermometer, the fall to -5 must be caused by an extra portion of heat to that extent absorbed from surrounding bodies, which not being able also to combine with the water and salt, thus becomes sensible to the ther mometer. OPENING OF THE VICTORIA-BRIDGE, ALL Canada was rejoicing on Thursday, the 24th this "hurried action" does not act mechanically by causing ⚫ While I assert this, I by no means wish to deny that such a sudden loss of heat that air, &c. (though at 50 or more) cannot restore it with sufficient rapidity to prevent a great fall in the thermometer. Thus, says Thoms, "Mercury may be frozen even in a warm room" by snow and chloride of calcium, and water may be frozen in a red-bot crucible, as Boutigny has shown, by anhydrous sulphuroas acid. (Etudes, &c., &c., 3ieme. edition, 1857.) It is clear that these and other marvellous facts stated in the volume just quoted, depend more or less on the fact that heat, left to itself undisturbed, moves much less quickly than clee tricity, and always requires a certain amount of time to establish its equilibrium. The long time the thermometer often takes to rise or fall shows the truth of this statement į but it is not easy to believe this at first, as we are generaliy accustomed to observe heat when circumstances oblige it to move very quickly. I may here add that another grand distinction between heat and electricity is, that the former seems to be able ta move through ALL kinds of matter, though through some with difficulty, including even ice (a non-conductor of eles tricity), as Tyndall's late experiments show, also Melloni's (see his tables, Ann-de Chini et Phys., Tom. 55). was about 12 minutes and a-half. Among the gentlemen in the car were the Hon. Mr. Cartier, Premier; Mr. M. Ross, chief engineer of the bridge; Mr. Blackwell, managing director, and several directors of the Grand Trunk road. Two of the tubes are not quite finished, but the bridge is expected to be fully completed and thrown open to traffic about the 15th inst. This will be exceedingly opportune for the trade of Canada, which is expected to derive a renewed impulse, as the water navigation has ceased. The traffic over the line is steadily increasing. The receipts for the week preceding the opening to Detroit, which took place on the 21st ult., amounted to 60,560 dols., being 10,000 above the receipts of the corresponding period of last year. The prospects of through Western freight are very good. GENTLEMEN,-I send you a specimen of light wood, which may afterwards, if you please, go to the Society of Arts. It is probably the same as that sent by Mr. Cunningham. I brought it from Brazil; it is the stem of the great flowering South American aloe, not a cactus. I do not think any of the cacti have any such wood. But light woods approaching this specific gravity, but of large size, are well known both in America and Africa, and are in America used for making Balsas or navigable rafts, while in Africa they are principally used for floating the heavier woods down the rivers. I do not, however, think that any such means can ever be useful for making unsinkable ships, for the space occupied must always be so comparatively great as to exclude any useful cargo, and all such bodies have the fault of rapidly absorbing water, and then of course losing their floatative qualities until again dried. Balsas or catamarans are always hauled up on the beach to dry after their short voyages. I think that more than anything else speed and bottom, i.e., economy of fuel, will decide the future naval engagements, at least as regards the material, and invulnerability or unsinkability are alike opposed to both of these, the one by in creasing the weight, the other by decreasing the space available for fuel. J. H. SELWYN. UNSINKABLE SHIPS. TO THE EDITORS OF THE " MECHANICS' MAGAZINE." Woolwich Dockyard, Dec. 6th, 1859. GENTLEMEN,-I am glad to observe that the suggested idea "unsinkable ships" is attracting the attention of your readers, whose remarks hold out the expectation that the subject will be thoroughly discussed. I am, however, not disposed to notice much of the banter with which it seems that the suggestion of original views on matters connected with practical science must be expected to be publicly received. In starting the idea of constructing ships so as to be unsinkable, I made no profession of having matured the details of such a project, for, first of all, the materials most advantageous for the purpose had to be determined, also the practical mode of applying them, which would greatly depend on the nature of the materials themselves; and ultimately the extent and varieties of application to which the principle can be beneficially adapted depends on considerations which, perhaps, no one individual is competent fully to appreciate; and all these con. tingencies are mutually dependent on each other. In the case now in question, it was the opening up of the Australian gold-fields that originated in my raind the idea of unsinkable treasure ships," for which purpose a mass of material built together solid, or if not suitable for being built together, filling up the compartments of a cellular construction so as to form a solid floating mass up to or a little above the load line of the vessel-such mass as respects its form and stability being, of course, constructed in accordance with the essential elements of naval architecture-would, I dare say, form a suitable bottom for such purpose. The treasure might be duly secured or embedded therein, and suitable accommodation for the crew would form the superstructure of the hull. Such was the original idea, and incidental circumstances, such as the supposed irresistible force and precision of modern ordnance, and the threatened introduction of the marine ram, gave rise to the suggested application of the system to ships generally. Every case of special application will, of course, demand special adaptation of practical details, the general result being that the aggregate mass of material, when immersed in water, shall not merely float itself, but be capable of supporting, in addition to its own weight, the load that the material for giving the floating power will be may be imposed on the ship. The distribution of a matter of arrangement in which great ingenuity may be displayed, and all the elemental principles of naval architecture will be called into requisition in the construction of "unsinkable ships," as is now the case in the construction of floating vessels generally.-I am, Gentlemen, Yours very obediently, CHAS. ATHERTON. THE LOSS OF THE ROYAL CHARTER. TO THE EDITORS OF THE "MECHANICS' MAGAZINE." GENTLEMEN, The inquiry into the loss of the Royal Charter having been closed, I beg to offer a few remarks, which you may perhaps deem not altogether useless on that unfortunate accident. not succeed. 66 It seems extraordinary that no reason is shown by the evidence why the operation of wearing did Wearing" (I may say, for the benefit of your non-nautical readers) consists in the turning of the ship's head from the wind in order to gain the opposite tack, as "tacking" or "staying" is the turning of her head towards the wind with a similar object. The Royal Charter, according to the evidence, had not for some time been able to keep to the wind, i.e., within six points, even with the helm hard a starboard. Tacking, therefore, would seem to have been out of the question. It was, however, tried but failed. But wearing ought, one would think, to have succeeded, and why it did not is the mystery, more particularly if the means were adopted to which I shall now refer. Admiral Paris, of the French navy, has recently spoken of some phenomena in the manoeuvring of steamers, which, I trust, are not unfamiliar to many of my brother officers. I do not think he notices the one which is applicable to this case. If in a heavy gale, the ship being on the port tack, with but little sail possible to be set (say a foretrysail or staysail), it be desired to wear, the screw, particularly if auxiliary, may be thus applied, bracing the yards, &c., as usual. From going a-head reverse and go astern easy, as quick as you can, the helm to be put very slightly to starboard. The ship's head will fall off quickly, because the screw gathers to port before it can act to force the ship astern. As soon as the wind is aft go ahead again. This can, of course, only be done (with a right-handed screw) if on the port tack, as the action is entirely caused by the differing immersion of the two blades, and the consequently differing force exerted by them; you will by this means, if skilfully done, lose but little if any more ground than if you had tacked, which is sometimes impracticable under such circumstances, and always uncertain. A curious and, I believe, hitherto unaccounted fact connected with paddle steamers is, that if you go astern, they will always turn their sterns towards the wind, as well where the paddles are in the middle as when they are nearest the bow. J. H. SELWYN, STEAM-SHIP ECONOMY. TO THE EDITORS OF THE MECHANICS' MAGAZINE." Woolwich Dockyard, 7th Dec., 1859. GENTLEMEN,-It is rather a trial of one's patience to have to repeat explanations in matters correspondents those who court public investigaof theoretical investigation. But in courtesy to tion in such matters must, it seems, frequently submit to such necessity; there is some satisfaction, however, in the fact that every such repetition in a public journal such as the MECHANICS' MAGAZINE attracts fresh inquiries towards the subject in discussion. With reference, therefore, to Mr. Cheverton's remarks in your last number (No. 49) on the construction and application of the formula Vз DI = C, I beg to repeat that in the Ind. h. p. calculation by this formula of the mutual relation of displacement, power, and speed of vessels of different sizes represented by their respective displacements, the coefficient (C) after having been under consideration, is assumed to be a constant practically ascertained for one vessel of the type number only for vessels of that particular type of immersed form, and in which the ratio of gross indicated h. p. to the effective working power is a constant number, or also assumed to be closely approximate thereto; also it is assumed that all other circumstances affecting the performance of the vessels are under similar conditions as usually implied by the term ceteris paribus. It is therefore only on the assumption of the co-efficient corresponding to the type that may be under consideration being known or approximately so, that any pretension is made to the mutual relations of displacement, power, and speed being determinable by this formula, that is, for either one of those elements being determinable the other two being given. It is also to be observed that two different types of steam-ship construction may possibly give the same co-efficient, that this can only be regarded as a coincidence in exception to the general rule. Presuming on these theoretical properties of the formula being confirmed by experience and conceded, it follows that the different co-efficients respectively distinctive of different types of steam-ship construction indicate the order of merit with reference to the mutual relations of displacement, power, and speed, in which the dynamic performance of vessels of different types may be rated or classified, and if instead of the indicated h. p. as the denominator in the formula, we adopt as its representative the consumption of coals per hour (W), the comparative co-efficient resulting from this formula will in like manner indicate the order of merit with reference to the dynamic duty capable of being performed by the respective ships thus tested in comparison with each other. I am, Gentlemen, your very obedient servant, METEOROLOGICAL TELEGRAPHY. A TALENTED author in one of his works on nautical science intimates that the electric telegraph might be advantageously used for the purpose of convey. ing notice of approaching storms. This novel ap plication of meteorological science may be appro priately termed "meteorological telegraphy," and I ventured to suggest to the Aberdeen Session of the "British Association for Advancement of Science" that they should appoint a special committee to consider and report upon some uniform plan for ascertaining the nature, force, and direction of sudden weather changes, and flashing warning telegrams, in such effective manner as to result in the saving of many lives and much property annually, especially by prevention of wrecks in our channels, and on the coasts. The proposition was submitted to the committee of the section of mathematical and physical science, and upon their favourable report the general committee of the Association passed a resolution recommending "application to the Board of Trade for such an arrangement as may further this object authoritatively." Illustrations and arguments in support |
