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work done, in the energy of nearly a thousand horses' power, at fifty miles an hour. How wonderful and yet how effective are the powers of this comparatively small machine! It is perfectly docile, and obeys the hand of its director with almost mathematical precision, and by the touch of a simple lever it regulates its movements to the nicety of an inch, or it bounds forward with a momentum, regardless of time or distance, and careers on its iron track like a dream of the Arabian Nights. In fact, we may almost regard them as realized, when we consider the smallness of the space and the organisms by which these wonderful results are attained. Apart from the flight of fancy, we arrive at the conclusion that these are facts already accomplished with a degree of certainty that ceases to be wonderful, except only to the uninitiated, who stares at what he is unable to comprehend. The general principles of the steam-engine and the locomotive are, however, easily acquired; and in this age of steam it should, in my opinion, form a separate branch of education for the benefit of both sexes, to whom it would be highly advantageous. It is a branch of knowledge of deep importance to the present and rising generation; and as steam and its application to the varied purposes of civilized life becomes every day more apparent, a knowledge of its powers and properties is much wanted, and ought not to be neglected.

I am the more desirous that instruction of this kind should be imparted to the rising generation in our public schools, as it would lead to practical acquaintance with instruments and machines in daily use, and would familiarize the more intelligent classes with objects on which, at the present day, we almost exclusively depend for the comforts and enjoyments of life. I do not mean that we should make scholars engineers; but they ought to be taught the general principles of the arts, in order to appreciate their value and to apply them to the useful purposes by which we are surrounded. It is by the acquisition of this knowledge that we shall overcome ignorance, so often fatal in the use of steam, and not unfrequently attended with danger to life and property. We might quote numerous examples of fatal boiler explosions and other casualties arising from this cause; and this want of knowledge is not only productive of danger, but it leaves important matters to be directed by the hands of incompetency, instead of being guided by the arm of intelligence. The introduction of steam and its application to such a variety of pur poses was shortly followed by that of gas, and this brilliant discovery we owe to the untutored mind of one of our first working mechanics, William Murdock of Soho, the assistant and contemporary of Watt. Mr. Murdock lighted up his own house and Soho about the year 1802 or 1803, and in 1804 gas was first applied to light Messrs. Philip and Lee's cotton-mills at Manchester. For some years it made little or no progress, but it was, in 1814, employed for lighting the streets of towns; and we are, therefore, indebted to William Murdock and carburetted hydrogen for the enjoyment of a pure and brilliant light in our streets and public buildings, and in almost every house and town in the empire.

Next to gas came steam-navigation, railways, and locomotion, and subsequently the electric telegraph. I will not, however, tire you with any detailed notice of these discoveries, however important they may be in a scientific point of view, but simply advert to those departments of science with which the members of this Section are more immediately interested. In taking even a cursory view of the machinery of the two annexes of the International Exhibition, we cannot be otherwise than struck with the multiplicity of the objects, the perfection of the execu tion, and the accuracy of the tools, together with the numerous devices by which these are attained. A very casual glance at this Exhibition when compared with that of 1851, and that of Paris in 1855, shows with what intensity and alacrity the public mind has been at work since the people of all nations were first called upon to compete with each other in the peaceful rivalry of mechanical art.

Taking the Exhibition as a whole, there is no very great nor very important discovery in mechanical science; but there is a great deal to be seen of a character both interesting and instructive. In land steam-engines there is nothing particularly attractive, if we except the growing importance of the horizontal, which is rapidly supplanting that of the beam or vertical engine. To the horizontal system may be applied economy in the first cost, and nearly equal efficiency in its application to mills and for manufacturing purposes. Another important feature in these engines

is their smooth and noiseless motion, their compact form, and the facility with which they can be applied as helps or assistants to those of larger dimensions. They are, moreover, executed with a degree of finish and accuracy of workmanship which cannot easily be surpassed.

In the agricultural department the same observations apply to this description of engine, where it is extensively used on a smaller scale. They are equally wel made, and the country at large are chiefly indebted to our agricultural engineers for many ingenious contrivances, and for their successful application, not exclusively to the farm, but to many other useful purposes in the economy of rural

life.

From the motive power employed in our manufactories and its adaptation to agriculture let us glance at the beautiful execution, compact form, and colossal dimensions of our marine engines, and we shall find, in combination, simplicity of form, concentration of power, and precision of action never before equalled in this or any other country. In this department of construction we are without rivals, and it is a source of pride that this country, as the first maritime nation in the world, should stand preeminently first as the leader of naval propulsion.

In locomotive as in marine constructions we are not behind, if we are not in advance of other nations, although it must be admitted that several splendid specimens of engines from France and Germany are exhibited by some of the best makers of those countries. There is, however, this distinction between the Continental locomotives and those of home manufacture, and that is, in this country there is greater simplicity and design, greater compactness of form, and clearer conceptions in working out the details of the parts. These operations, when carefully executed to standard gauges, render each part of an engine a facsimile of its fellow; and hence follows the perfection of a system where every part is a repetition of a whole series of parts, and, in so far as accuracy is concerned, it is a great improvement on the old system of construction.

The other parts of the Exhibition are well entitled to a careful inspection. In minerals and raw material the collections are numerous and valuable to an extent never before witnessed in any Exhibition; and the articles, fuel and ores, will be found highly instructive. The machinery for pumping, winding, and crushing is upon a scale sufficiently large and comprehensive to engage the attention of the mechanic and miner, and it is only to be regretted that in every case competent persons are not in attendance fully prepared to explain and initiate the inexperienced student in the principles of the workings, and the cases of instruments so neatly classified and spread before him for instruction.

In the machinery department, although there is nothing that strikes the observer at first sight as new, yet there are many useful improvements calculated to economize labour and facilitate the operations of spinning and weaving; and in toolmaking there never was at any former period so many hands and heads at work as on the occasion pending the opening of the Exhibition. Some of the tools, such as the turning-, boring-, planing-, and slotting-machines, are of a very high order; and the tool-machinery for the manufacture of fire-arms, shells, rockets, &c., is of that character as to render the whole operations, however minute, perfectly automaton or self-acting, with an accuracy of repetition that leaves the article, when finished, identical with every other article from the same machine. Such, in fact, is the perfection of the tool-system as it now exists, that in almost every case we may calculate on a degree of exactitude that admits of no deviation beyond a thousandth part of an inch.

Amongst the many interesting mechanical objects exhibited in the two annexes may be noticed as original, the spool-machine, for the winding of sewing-thread on bobbins, the machine for making paper bags (invented by a pupil of my own), the saw-riband machine, and others of great merit as regards ingenuity of contrivance and adaptation of design. In manufactures, in design, and in constructive art, there is everything that could be desired in the shape of competitive skill; and, without viewing the success of the Great Exhibition of this year in a pecuniary point of view, we may safely attribute its great success to the interesting and instructive character of the objects submitted to public inspection.

Irrespective of the Exhibition, with its invaluable and highly finished specimens,

we have briefly to notice some of the improvements and changes that have taken place in the construction of ordnance and the art of defence, and to chronicle some of the most important results which have placed the whole of our naval and military armaments in a state of transition. It is now well understood that His Majesty the Emperor of the French was the first to apply iron plates as a defence to the sides of ships, and that ships of war protected with a given thickness of plate 4 inches were invulnerable to shot or shell. For a considerable length of time this opinion was prevalent, and was acted upon both in this country, France, and America. The experiments instituted by the Admiralty and War Office have, to a great extent, dispelled these notions; and it has been proved that a smooth-bored Armstrong gun, with a 150-lb.spherical shot, can pierce a4-inch-thick plate and 18 inches of teak. In fact, it has been proved by experiment that no vessel yet constructed is able to carry armour-plates of sufficient thickness to resist such powerful ordnance as has been brought against them.

Every effort has been made on the part of the Government to determine experimentally the properties of iron best calculated to resist shot, and the greatest possible care has been observed, both in a chemical and mechanical point of view, to secure the very best description of iron for that purpose. All these facts have been ascertained, as also the penetrating powers of different descriptions of ordnance as compared with the thickness of the plates to be pierced. In this position the balance of force to the resistance of the plate was in favour of the gun, but with this qualification, that the gun had to sustain an explosive force of powder equivalent to one-third the weight of the shot, a charge which the gun was unable to bear. Under ordinary circumstances, with the usual charge of one-eighth the weight of the shot, it might reasonably be inferred that the balance was on the side of the plate, and that guns of such heavy calibre were insufficient in strength to sustain these tremendous charges of powder. Again, it must be borne in mind that these results were only produced at certain distances, and under certain conditions of heavy charges of powder and a short range of 200 yards.

The inquiry was thus hanging on the balance, when it was determined to ascertain the effect of the large Horsfall gun of 22 tons weight with a charge of 75 lbs. of powder and a 300-lb. shot, against a target representing the 'Warrior,' with her 18 inches of teak and 4 inches of iron. The result of this experiment was the penetration of the mass, with a huge opening in the side of the target upwards of 2 feet in diameter. This experiment is probably not calculated to apply to ships of war carrying ordnance of such immense weight, but it is greatly in favour of forts, where an enemy's vessel may be struck at a distance of 1000 yards.

Passing from the Horsfall gun, we now come to the last and most important experiments with the Whitworth gun: the first was a 12-pounder field-gun, and the second a 70-pounder naval gun; both of the guns were rifled. These experiments are very instructive, and I probably could not do better than quote from the "Times,' of September 18th, a statement of the effect produced by these guns:-"It will, perhaps, be remembered that a decided difference was established very early in the controversy between the penetrating powers of solid shot and those of shell. Solid shot at one time failed, and at another time succeeded, against armour-plates, according to the modified conditions of the experiments; but shells failed absolutely and invariably. No shell could ever be driven through even a moderately thick plate of iron, and it was concluded, therefore, that this, the most dangerous and dreaded species of missile, could undoubtedly be kept out of a ship by a thin casing of armour.

"Accordingly, as a reduction of a ship's armour to the least possible weight was of great consequence, especially in small vessels, gunboats and other craft of the like description have been built in some countries with 24-inch or 2-inch armour-plates, and considered effectually shell-proof. On Tuesday, however, Mr. Whitworth entered the field with two of his pieces, for the service of which he had specially prepared some flat-fronted, hardened shells. The 12-pounder, at 200 yards, presently sent these shells through a 2-inch plate backed by a foot of timber; from which simple piece of evidence the conclusion is inevitable, that vessels protected to that extent only are shell-proof no longer.

"But in the trial of the 70-pounder an additional result was obtained. It has

been suggested that if, instead of employing a given thickness of iron in one solic piece, the armour of a ship were divided into two plates, each of half that thickness, and these plates were separated by a certain space from each other, the re-s. ing power of the structure might be much increased. The theory was that the first plate, though it would doubtless be pierced, would so deaden the force of the shot that the second plate would repel it; and, indeed, as regards solid shot, the GRA tion remains still undecided. With respect to shell, however, or rather Mr. Waitworth's shells, we are not left in doubt even on this point. The 70-pounder wa trained against a target constructed on this principle of a double side. A strong oak frame, armed with 4-inch plates, was attached to a second plated to the depti of 2 inches, an interval of two or three feet being left between them. The shel from this gun, fired with 12 lbs. of powder only, pierced the outer side of the target completely, oak and iron together, after which it burst inside the frame and shattered it to pieces."

From this statement we learn, that 4 inches of solid iron and 9 inches of wood are no protection against shells discharged from a moderately sized gun, and that ne gunboat, such as those on the American waters, could prevent the entrance of these dreaded and destructive missiles. In point of fact, Mr. Whitworth, with a rifled gun lighter than the 68-pounder, could destroy them by his steel-hardened shells at a distance of 1500 to 2000 yards.

Since the above was written another experiment has been made with a still larger gun, rifled on Mr. Whitworth's hexagonal principle. This gun was of large calibre, 120-pounder, at a distance of 600 yards, and the results seem to prove that the side of a vessel like the 'Warrior' is no longer shell-proof. In these experiments 130-lb. solid shot, with a charge of 23 lbs. of powder, went right through the 41inch armour-plate and lodged in the teak backing behind. A shell of the same weight, and a charge of 25 lbs. of powder, also penetrated the armour-plate and exploded, tearing the wood backing, and lodged on the opposite side.

From these more recent experiments we may infer that the victory is on the side of the gun, and that it may be difficult, under such fearful odds, to construct ships of sufficient power to prevent their destruction by the entrance of shells. Other experiments are, however, in progress, and means may yet be adopted to solve the question of armour-ships versus shot and shell.

On the Importance of Economizing Fuel in Iron-plated Ships. By E. E. ALLEN. Iron-plated ships, to be efficient, ought to be able to carry coals for fourteen days; but in consequence of the weight of the armour, and the present mode of generating and using the steam, only coals enough for seven days can be carried. In future wars, despatch in going to the seat of war, and high speed in manoeuvring, will be necessary; therefore much fuel must be used; hence the desirability of studying how to economize fuel. The deficiency of boiler-power in the Royal Navy is too well known. Modern inventions have increased the displacement of ships: thus, the armour, coals, and machinery are about equal in weight; and 1000 horses' power will consume 200 tons of coal a day, under full steam, say at ten knots per hour; but the necessary power for increasing the speed from ten to twelve knots demands double the fuel; and if the speed be increased to sixteen knots, the amount of fuel must be quadrupled. Some of our new war-ships only move at 91 knots an hour, whereas it is generally allowed they should make 15 knots; 5000 miles ought to be steamed without re-coaling, but only one-third of that distance can be accomplished. As a proof that the boilers are too small, it may be affirmed that none of the ships in the Royal Navy can work full steam, and keep the throttle-valves open, for more than a few hours at a time. Six-hundred horse-power boilers should be used where only 400 horse-power boilers are now used. Coal is the only item in which weight can be saved. The merchant vessels only consume half the coals (for ships of the same size) of those in the Royal Navy. Cornish engines consume 2 pounds of coal per horse-power per hour; 2 pounds ought to be the limit in marine engines; but 6 pounds are generally used in the Royal Navy. He proposed the following methods for economizing fuel:-To proportion the boilers to the steam required; to increase the capacity of the cylinders, but not the length of the stroke;

to superheat the steam; to jacket the cylinders to warm the injection water; to work the steam expansively by having two cylinders, a small one at the back of the large one, or concentrically within the large one, and to let the steam into the small cylinder first. Although he recommended this to our Admiralty in 1855, no notice was taken of it. The Swedish Government have adopted it in their new gun-boats, and it obtained a medal at the present Exhibition. By these arrangements for economy, and with better-designed engines, 17,000 tons of coal per day might be saved throughout our fleet; but now, after steaming 2000 miles, the ships have to creep into port, under canvas, to be re-coaled. 40 per cent. of power might be added, and therefore a greater speed of one-and-a-half knot per hour obtained, without greater displacement; and 14 tons per horse-power per annum, or a million tons of coals per annum, for the whole fleet might be saved.

On Artificial Stones. By Professor D. T. ANSTED, M.A.

In this paper the author described the various materials and contrivances used for the purpose of replacing stone where natural stone could not be advantageously procured. He described, in succession, terra cottas, cements, and siliceous stones, pointing out the character, properties, uses, advantages, and disadvantages of each. He alluded to experiments made in the laboratory on the various methods suggested for preserving stone by a Section of the Committee recently appointed by the Board of Works in reference to the Palace of Westminster; Dr. Hofmann, Dr. Frankland, Mr. Abel, and the author being members of it. During their investigations a remarkable material was submitted by Mr. Ransome for their consideration, and its discovery arose out of Ransome's method of preserving stone by effecting a deposit of silicate of lime within the substances of the absorbent stone, saturating the surface with a solution of silicate of soda, and then applying a solution of chloride of calcium; thus producing a rapid double decomposition, leaving an insoluble silicate of lime within the stone, and a soluble chloride of sodium, which could afterwards be removed by washing. To prove this, Mr. Ransome made small blocks of sand in moulds by means of silicate of soda, and then dipped them in chloride of calcium. The result was the formation, almost instantaneously, of a perfectly compact, hard, and, to all appearance, a perfectly durable solid. Mr. Ransome at once adopted the process for the formation of an artificial stone which, the author of the paper considered, would combine the advantages, and avoid some of the disadvantages, of other artificial stones. Experience, however, can alone be the test of its durability. A specimen weighing two tons was shown in the International Exhibition, and the substance is used in the stations of the Metropolitan Railway. It is cheap, and can be made, on the spot, of almost any rubbish or material, and of any form or size. Experiments made by Mr. Ransome show that, as compared with Portland stone or Caen stone, a bar with section 4 inches square and 8 inches long, suspended midway between supports, sustained 2122 lbs., while similar bars of Portland and Caen stone broke respectively with 750 lbs. and 780 lbs. The adhesion of the stone was shown by weights suspended from a piece prepared to expose a sectional area of 5 inches. Caen stone separated at 768 lbs.; Bath, at 796 lbs.; Portland, at 1104 lbs.; Elland Edge, at 1874 lbs.; Ransome's, at 1980 lbs. A cube of 4 inches of Ransome's stone sustained 30 tons.

Unsinkable Ships.

By CHARLES ATHERTON, late Chief Engineer in H.M. Dockyard, Woolwich. The author observes that competitive rivalry in the construction of ships of war with a view to their being "invulnerable," and in the construction of ordnance with a view to its being effective for penetrating the build even of armoured ships, appears, from the experiments which have been carried on at Shoeburyness, to be a question involving unlimited expenditure in possibly abortive ship-building, the result of which rivalry between ordnance and iron plating, being dependent on future invention, does not admit of present definite solution.

Nevertheless the principle of "invulnerability" in the construction of ships of war by the agency of iron plating having been originated and adopted by France

present the most effective system of naval construction, though admitted

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