thus inserted. Whilst employing this system on the Great Northern Railway very extensively, Mr. Sturrock has found it necessary to place a key on each side of the weld of the tyre, as an additional security against its flying in case of fracture on account of a defective weld.

It cannot be considered that the tyre is so firmly secured to the portions of the rim between the keys, as, when a more continuous means of fastening it is employed. In a method which he has proposed for engine wheels, Mr. Beattie has secured the outer side of the tyre by means of a groove fitting on a notch in the rim of the wheel O, Fig. 2, and has attached it, near the inner edge, by bolts screwed into it from the inner surface of the rim, and inserted at frequent intervals

PP.

Mr. Gibson inserts annular keys extending all round the circumference DE, Figs. 3 and 4, and hammers the inner edge of the tyre down upon indentations which are formed on these, to clench them, at intervals; or else he hammers down that edge directly upon the rim, as shown at F, Fig. 5. The annular keys are an improvement upon the keys at intervals, inasmuch as continuous fastenings are obtained by their employment; and it is said that there is no difficulty in removing a tyre thus attached to the wheel, and in replacing it. As in the former method, the bearing of the rim upon the tyre is reduced to admit of the insertion of the key, however, and the use of the key, whether continuous or not, appears, if it does not detract from security, to be an unnecessary complication.

Mr. Mansell's tyres, Fig. 6, are affixed to wooden discs. They are not shrunk on, as in the case of other methods, but, being themselves bevelled, they are forced on to a bevelled surface by hydraulic pressure. Two grooves, Z Z, are formed in the tyre, and two securing rings, which are fixed, one at each side, into these grooves, are bolted together through the timber discs, by means of screw-bolts and nuts placed at frequent intervals. Mr. Brotherhood's tyres, Fig. 7, are also fixed to the rims of the wheels by means of two rings, NN, each of which has a projection on its inner surface fitting into a recess in the tyre. These rings are riveted together by means of rivets (one of which is shown in dotted lines) placed at the junction of the spokes with the rim. A piece of wood, W, keeps the rings apart inside the rim. These two methods, which proceed, as far as the attachment of the tyre is concerned, upon the same principle, are a little complicated, but afford, undoubtedly, great security,

Messrs. Cabry and Owen employ a second dovetail, H, Fig. 8, between the rim and the tyre, similar to that at the outer edge G; and, after shrinking the tyre on to the wheel, they clench down a portion of the interior of the tyre, K, rolled on it for the purpose, to secure it in its place. This portion is only clenched down at intervals, to admit of the tyre being afterwards removed and replaced when necessary. be feared that in this system the dovetailed surfaces might not in all cases be fitted with sufficient accuracy to ensure a good result; and that, even if they did so in the first instance, the tyre might alter its shape as it became thin from wear, to an extent that would destroy the efficiency of the fastening.

It is to

Mr. Burke's tyre is rolled out into the shape shown in Fig. 10, and is welded, turned to a true surface, heated, slipped on to the wheel, and allowed to contract, in the usual manner. It is then turned over; the portion M is heated to a red heat; and that portion is hammered down against the rim all round its circumference.

All of these methods of fastening tyres are superior to that which is now commonly adopted, and any one of them may be considered, when the materials are well selected, and when careful workmanship is employed, to afford a high degree of security.

That which is shown in Figs. 9 and 10 is, perhaps, the most simple, and the most likely to come into general use. The disadvantage that it would

present to some eyes, in the impossibility of taking it off the wheel, for tightening or repair, after it is once fixed on, and replacing it again in its original condition, is by no means so serious as it might appear to be at first sight. Either security must be more or less sacrificed when this condition is maintained, or else some more complicated arrangement connected with the rim, such as those of Mr. Mansell and Mr. Brotherhood, must be employed; but, in truth, the cases in which repairs, requiring the removal of the tyre, become necessary, when good wide tyres are carefully attached to well-constructed wheels, are so rare that they may fairly be left out of consideration; and a tyre which has worn slack, and is re-shrunk on the wheel, will almost always become slack again within a short period. Such an operation is hardly worth performing; and when a good tyre is securely fixed, in the first instance, by means of an efficient continuous clipping attachment, it will then be worn out to the thinnest state in which it is fit for use, without any apprehension of danger, in consequence either of its fracture or of its slipping off the wheel.

The real disadvantage of this mode of fastening appears to me to lie, either in the liability to an imperfection of fit between the rim and the tyre, or of a want of parallelism in the dovetail surfaces in the first instance; or else in an alteration of the shape of the tyre, by spreading or otherwise, from wear and tear, which must always become greater as the tyre becomes thinner, and which would, therefore, reader the fastening less and less secure, at a time when it was more and more necessary that it should be efficient.

To prevent the possibility of such defects, I think that a modified mode of fastening might be adopted, such as I have shown in Figs. 11 and 12, which would be well adapted for all wheels, which would give increased security at all times, and which would remain efficient up to the last, becoming, indeed, more secure as the tyre got thinner, and hollow from wear.

In the application of this arrangement, the tyre would have to be grooved at O, Fig. 11, when it was turned to its proper size, as in the cases of the tyres shown in Figs. 2 and 6; and the rim of the wheel would have a notch on each side of it. The tyre should not be in too heated a state when the wheel is slipped into it, as the rim would not

in that case penetrate into the recess at 0; but it has been found by experience that a sufficient heat may be imparted to the tyre in shrinking it on, without any difficulty in slipping it into a recess of suitable dimensions being encountered. Fig. 11 exhibits the condition that would exist between the wheel and tyre, when the wheel is first inserted; and Fig. 12, the finished tyre, after the inner edge at Q is hammered down upon the rim.

Although there is greater fear in general, with regard to a slack tyre, or a loose tyre, or a broken tyre, the most dangerous tyre of all is that which has been shrunk too tightly on to the wheel, and whose state of tension renders it ready to fly upon any violent blow being administered to it, by a bad joint, or an uneven crossing, in the ordinary This is the sort of tyre that yields the clearest ring to the hammer of the carriage examiner, and that inspires him frequently is the tyre that ought in reality most to be with the greatest degree of confidence; but this dreaded; and this is the description of tyre that occasioned the present accident.

course of traffic.

But even when a tyre has been placed upon the wheel in a condition of too much strain, there ceases to be danger, when it is secured to the wheel in some maunet, such as that now indicated, in which it is prevented from separating from the rim, or, as it is termed, from flying, when fracture takes place.

TUCKING AND PLAITING GUIDE SEWING MACHINE. American patent for an invention which consists in -Warren L. Fish, of Newark, N.J., has secured an sewing machines, whereby the edge of the fold of the an improvement in tucking and plaiting guides for tuck or plait is kept infallibly at a uniform distance from the needle.

ON THE IMPOSSIBILITY OF PUDDLING. IRON WHICH CONTAINS COPPER.

By Dr. C. LIST,

IT has been stated as a matter of belief among practical iron-workers in Germany, that pig-iron which contains copper cannot be puddled; assertions having even been made, that when one puddler wishes to annoy another he will sometimes throw a bit of copper-a small coin for example→ into the furnace, so that the iron cannot be made to "rise."

Without giving full eredence, as yet, to this statement, Dr. List mentions that he has observed two instances which go to prove that it may be correct. In the case which lie has more particularly described, none of the phenomena which ordinarily occur when iron is puddled appeared. Some 400 lbs. of pig-iron having been placed in the furnace, were melted in the course of half-an-hour, at which time a sample taken from the molten mass was perfectly white, but the usual evolution of carbonic oxide, and consequent swelling or "rising" up of the mass of scales, &c., about the iron, did not ensue. On the contrary, by the time that the balling together of the iron should have commenced, it was evident that the charge could not be worked off; it was therefore removed from the furnace, after having remained there about threequarters of an hour. As the melted metal was flowing out it emitted numerous beautiful blue sparks, which were also produced when the metal in the furnace was stirred. The sparks were regarded by the workmen as an indication that the iron contained copper.

The amount of metallic iron which remained weighed 240 lbs., 160 lbs. having been lost in the scales and slag. Analyses [for details of which see the original memoir] were made of the original pig-iron, (1.); of the sample taken, as previously mentioned, from the melted iron, as it lay beneath the scales (II.); and of the iron after it had been removed from the furnace (III.).

It was evident, therefore, that the 400 lbs. of

pig-iron used did really contain nearly a pound. and a-half of copper. It appears, moreover, that copper cannot be removed from iron by puddling. Calculating how much copper ought to be left in. furnace, in case none had been lost in the slug, it the iron which was finally removed from the is found that there should be 0.58 per cent.,, almost exactly the quantity which was obtained in analysis No. III.-Dingler's Polytechnisches,

Journal.

WILSON'S IMPROVEMENTS IN CANNON. MR. J. WILSON, of Birmingham, engineer, has recently obtained a patent for improvements in the manufacture and construction of ordnance,

which consists, first, in the following method of making the barrels :—

A series of hollow cylinders or tubes of metal a, b, c, are taken, the tubes being of a length equal different diameters. to that of the cannon to be manufactured, and of The respective diameters being so arranged that they very nearly fit one another, that is to say, the tube b will very nearly enter the tube c, and the tube a will very nearly enter the tube b. The interior of each of the tubes is finished by boring, and the exterior by turning; the said tubes being of such sizes re spectively, when fini hed, that they will not pass into one another. Each tube is fitted upon that next.below it in size by shrinking.

Sometimes the patentee makes a series of longi tudinal grooves or channels on the outside some or all of the tubes, excepting the external one, for the circulation of air or water, to keep the piece cool when in use. The outer tube c is made thicker at the breech end than at the muzzle end, and the patentee prefers to attach

A PATENT has been recently obtained by Mr. J. Lark, of Strood, for improvements in grinding cement and other substances, and in the machinery or apparatus connected therewith. For this purpose the patentee employs horizontal millstones as usual, and drives the running stone, by forming a crank on the vertical shaft or spindle of the stone, and connecting the same with a horizontal steam cylinder which is mounted on a bed plate, as represented in the above engraving. Where several such mills are employed, they are arranged side by side, and the bed of the steam engine is so constructed that it may traverse on rails or guides in front of the several mills. A fly wheel is mounted on the spindle of each of the mills if they are required to do heavy work. a is a wooden frame of sufficient length to carry as many pairs of stones band bas may be required; the upper stone is mounted on the vertical spindle c, which works in a bearing at d, and at its lower end is stepped on to the lever e; f is a centre, about which this lever is capable of turning; and g is a shaft with a worm at its lower end passing through a nut on the lever e, so that by turning the shaft g by the hand-wheel h, the upper stone may be raised off the lower one, and set at any required distance is a crank; to this the connecting rod of the engine from it; i is a flywheel on the spindle c; and cl is coupled when the stones are to be put to work. The cylinder and other parts of the engine are mounted on a bed as before explained. The engine when at work is bolted down to the frame by bolts m, m, as shown, and the valve is worked by an excentric rod n actuated by an excentric o on the vertical shaft c. When the engine is to be shifted to another pair of stones the holding-down bolts m, m, are slacked or removed, and the connecting and excentric rods uncoupled, the engine bed can be traversed along the guides. When it has arrived opposite another pair of stones, the bed is again bolted down, and the connecting and excentric rods are coupled up to the crank and excentric on the upright shaft of these stones. The supply of steam is maintained either by jointed pipes, or by introducing or taking out lengths as may be required. It will be evident that the frame a may be made circular in place of straight, and the several pairs of stones arranged round in a circle, the engine being then mounted on a turntable in the centre.

PIROTTE'S IMPROVED CONDENSERS. MR. A. PIROTTE, of Liege, Belgium, engineer, has just completed a patent for "improvements in the construction of condensers," which consist in a novel mode of constructing condensers whereby their efficiency will be increased, and they will be less liable to get out of order than hitherto.

Porcelain is now ornamented with gold, in Paris, by hydrofluoric acid and electroplating, as follows:The porcelain is first covered with a varnish, upon which the drawing is made with a fine point. The subject is then eaten out by the acid vapours, and the vessels afterwards plunged into silver or gold baths, The accompanying engraving represents a rectwhen a deposit of these metals is determined, in the In some cases, certain coloured mineral powders are material, closed at top by a cover which is bolted parts corroded by the acid, by means of galvanism. angular vessel of cast-iron or other suitable rubbed into the tracings left by the hydrofluoric acid, thereto. This vessel is divided into three comand fixed there by the action of heat, so that any departments or chambers by two horizontal partisign can thus be produced. tions be, which extend from end to end. Fitted

was repaired; and wouid, of course, be the same to every kind of train.

Cause 14. In the train now suggested, the carriages being inclosed in and suspended from the axis of a cylinder, and the centre of gravity being close to the rails or the point of support W (see diagram Figs. 1 and 2) could not upset by any power less than one sufficient to lift up and turn over the whole train, which is equal to being practically impossible, as no such power could be brought to bear upon it accidentally.

Causes 16 and 17. The greatest velocity lay in the surface of the iron cylinder, the revolving of which upon its axle would be so comparatively slow that no danger from this cause could possibly exist, and the carriages being suspended within protected by the external iron cylinder could not by any means take fire through sparks from the engine.

It is not unimportant to notice that, in the train now recommended no danger could arise from deficient action of the breaks, as no such things would be required. The centre of gravity or the greatest weight being near the rails at the point W, and the cylinders being moved by force applied at the axis C, the moment that force (or traction) is suspended the whole train will quickly come to a state of rest. Hence the engineer, or guard, will have much greater control over the velocity and stoppages than they could possibly have over trains of the ordinary kind. A very good illustration of this tendency in the cylinder train to stand still on the power of traction being suspended, may be observed in a common garden roller or a timber carriage. The weight is generally hung from the axis to the lower edge of the roller, and the whole moved by pulling or pushing at the axis. The centre of gravity being always at the lowest point, near the ground, whenever the moving power is diminished the roller immediately tends to become stationary-the axis and the centre of gravity being equally in the "line of direction," according to the simplest mechanical laws the whole moving mass must necessarily stand still the moment the traction power ceases. This very important characteristic of the cylinder train arises from the fact that the cylinder containing the carriages, instead of shooting forward, like the present railway carriages, merely rolls over the rails, and therefore cannot possibly obtain that momentum which causes so much difficulty in stopping, and renders a collision so dreadful in its results.

From a careful consideration of the various points now explained, it will be evident that nearly the whole of the causes which have hitherto operated so fearfully to the sacrifice of life, and which have caused so much suffering and apprehension as well as destruction of property and public confidence, would be entirely removed by the adoption of the rolling or cylinder train in place of what may be called the projectile system now in practice. Chelsea, March 5, 1861.

PARALLAX.

THE ARMSTRONG JOB.

MR. EDITOR,-Knowing generally the accuracy of your Journal, and the care taken not to mislead your readers on any subject, I was not surprised to find in the recent revelations in the estimates in the House of Commons, that your first statement of the Armstrong Job on the 9th November last was so fully confirmed by the admissions of the Under-Secretary of State, Mr. T. G. Baring.

Before you advanced any opinion, you knew that Parliament had granted two millions for Armstrong guns, "unsight unseen," as far as any practicable proof existed of their efficiency for service, and that these guns were contracted for without advertising for tenders as usual for Government supplies, that other skilful manufacturers of similar weapons might compete at least for the job, instead of confining the monopoly to one factory, with two shops, one at Woolwich and the other at Elswick.

You were the first to publish, on the 9th November last, it would almost seem from Sir William's own books, the exact number and description of the first batch of the Armstrong rifle guns, namely, 20 100pounders, 25 40, 36 25, 16 25 (boat guns), and 354 12-pounders, weighing from 8 to 6 cwt. each, total 451 guns.

You merely added, "If of the two millions granted by Parliament, £1,500,000 had been spent already, and of this, £500,000 expended in experiments and the plant at Elswick and Woolwich, then one million would remain to be accounted for, as the cost of the 451 guns manufactured, being no less than the amazing sum of £2,000 cach, or nearly so.

No other journal having brought the Armstrong job to light, the Times followed your example by

Had the suffering taxpayers been treated with only common justice by Sir William, the honour of knighthood, and the additional unmerited picking of twenty thousand pounds reward would have followed the best gun made, instead of preceding the worst, without any valuable practical proof, that 20 of th first 100-pounders were not worthless as well as others for naval and military warfare. A TAXPAYER.

The amazing sum of £2,000 for his improved guns seemed to alarm the contractor, as the Times was told you might as well have said £10,000 each, while you were about it, but he thanked you for having raised the question, as it enabled him to inform your readers that "the Government could be supplied with any THE number of the new 12-pounder guns (of which 351 had been manufactured before the discovery was made) at two-thirds of the price of the old 12pounder brass guns, the cost of which was £170."

It appears, therefore, that it was high time for you to be "dignified" enough to speak out, and for the Times to follow your example. For after throwing on the broad shoulders of John Bull the whole, or a large portion at least, of half a-million sterling for experiments, explosions, mishaps, breakdowns, and plant at Woolwich, and the other shop at Elswick, together with a corresponding portion of the other million, Sir William suddenly makes a discovery, more worthy of a patent than all the rest, that others would, if he did not, supply 354 of the same sort of 12-pounder, or any other number, at "two-thirds the cost of old brass 12-pounders, £112 6s. 8d. each," instead of £2,000 each, being among the "incomprehensible charges" equal to £708,000, whereas at the old brass gun rate the charge would be reduced down to only £39,761 thus saving Her Majesty's Government in the single item of 12-pounders, £668,236 sterling for one lot.

Sir William Armstrong could not, and did not, venture to disprove any one of your statements, you challenged him publicly to avow, on his honour, that any of the facts were materially different to what you represented, and he has remained ever since in the most happy state of "dignified" quiescence.

"ex.

Mr. EDITOR,-This Grenade when thrown from fall upon its bottom like a shuttle.cock. an upper window or the roof of a house, will always When charged, the percussion appliance hangs by its side attached by a slip of elastic twine. This appliance has a percussion cap in its centre, and when the grenade is about to be used, the elastic twine permits the appliance to be placed on the nipple at the bottom of the grenade. This grenade may also be used as à passenger signal to communicate with the guard and engine-driver of a Railway Train. J. NORTON.

ORIGIN OF THE GULF STREAM.

Mr. C. W. DENISON, as the result of eight years' investigation, submitted the following proposi tions to the Polytechnic Association of the American Institute a short time since.

1. The Gulf Stream is of subterranean origin. 2. Its progress, in a certain direction and rate, is caused by the shape and revolutions of the planet.

4. The Gulf Stream is fed from beneath by a constant flow of waters. Some of these are the Mediterranean and other adjacent seas.

The Times, to whose judgment Sir William Armstrong appealed most confidently for a verdict of acquittal, seems to confirm rather than contradict your statement. For with reference to Mr. T. G. Baring's edition of the estimates, it says "the charges are perfectly incomprehensible." Mr. Baring 3. It is heated by interior volcanic fires, supplained that neither the decrease shown in the esti-plied from the igneous portions of the globe. inates, nor the increase shown in the number of men represented, were anything like the facts. The cost of the Armstrong gun, which General Peel after a careful study of the estimates, had made out to be a fraction of £160,000, the Under-Secretary declared would be a good £800,000 for at least £800,000 would be applied for these guns and their accessaries,' and this too in the very figures before the House, so hard is it even for an experienced eye to pick out the truth of these accounts. The estimates increase steadily and are incomprehensible all the while; nobody sees where the money goes to, or what is got for it."

You observe in your last Journal:-" At the present moment the construction of the Armstrong guns is a question not of safety, but of money. Unfortunately we cannot spend just now another million upon experiments. Sir William's guns have already cost us two millions, and, as Mr. T. G. Baring informs us, that 945 have been manufactured (in despite of all the glaring proofs in China and elsewhere of the defective construction of the first batch of 451), each gun has cost over £2,116. If the statement be inaccurate, we hope some one will set the public right, for we find the Times stating that some two millions are ascribed to the reconstruction of our ordnance;' but here again the accounts were 'perfectly unintelligible.' state how many of the additional 495 new rifle Will Sir William Armstrong be honest enough to are now charged at £112 6s. 8d. each? being the price he declared himself in the Times, in November last, willing to supply his 12-pounders at, that others might not have the job instead of himself, and why he did not make the discovery long before he expended one million and a-half of money granted by Parliament, or how much less?

guns

5. The colour, heat, current, motion, animalculæ, sedges, taste, odour, and all the other peculiarities of the Gulf Stream, prove it to be subterranean in its origin and progress.

shore of the Gulf of Mexico, have nothing to do with the origin, characteristics and progress of the Gulf Stream.

6. The trade winds and the formation of the

The colour of the Gulf Stream, he said, is deep blue. That this is not caused by its saltness is evident, first, because salt would not make it blue; and, second, because it is no more salt than the adjacent waters which are not blue.

The colour is caused by the sulphate of copper which the water contains in solution. The water

enters the Mediterranean sea from the ocean at

the rate of three miles an hour, and this is exactly the rate of the Gulf Stream, indicating a connection between the two. His explanation of the phenomenon is that the water of the Mediterranean sinks into a vast chasm in the earth at

cylla and Charybdis, and thence passes westward through the interior of the earth, becoming heated by volcanic fires, and charged with the sulphate of copper, until it finds vent in a vast chasm along the American shore. The water of the Gulf Stream is in perpetual eddies, as though boiling up from below. The animalcula of the Surely, then, it is quite time, if the memorial Gulf Stream are not found in the Gulf of Mexico signed by 60 honourable patrons of national economy or the Bay of Campeachy, but are identical with to Lord Palmerston for retrenchment be not all smoke or "much ado about nothing," to ask for the report those found in the Mediterranean sea. The sedges of General Crofton and Major Hay on the Armstrong found in the Gulf Stream are identical with guns sent to China. This report will practically the fuci of Egypt, and are probably derived from illustrate the wisdom of granting two millions for the Nile. The odour and taste, derived from the rifle guns, "unsight, unseen," of trying all kinds of ex-sulphate of copper, are found only in our Gulf periments at the sole risk and cost of the taxpayers of Stream, and in similar streams. The reason of the country and of making more than one thousand the failure of the Atlantic Telegraph was probably, rifle guns before even the contractor, Sir William Armthat there is a deep chasm opposite the coast of strong, had brought the principle of his invention to Ireland, the bottom of which no cable could any sufficiently satisfactory and practicable test to justify the use of them, when offered to the Tartar reach. The geysers of Iceland rise and fall with cavalry or any other cavalry in the world, much less the tides, indicating a connection with the ocean, before a single gun was sent to China. while warmed by volcanic fires.

Literature.

The Merchant's Counting House Companion, consist.

ing of Commercia! Tables in Daily use in the various Branches of Mercantile Life. By GEO. J. GRAHAM. London: Longman, Green, Longman, and Roberts. 1861.

To the preparation of this work the author has devoted the leisure after-business hours of seven years. It contains, 1st, Reckoning Tables, showing the value of any number of articles at different prices or rates, including fractional tables. 2nd, Tables showing the value of any quantity of merchandise from one pound to fifty tons, at given rates, per cwt. or ton. 3rd, Tables showing the commission, brokerage or discount on any sum from one pound to fifty thousand. 4th, Tables of moneys, weights, measures, banks, forms of bills, squares, cubes &c. 5th, Wages tables for sixty hours to a week's work according to the Factories' Regulation Bill, and 6th, Tables comparing French and British weights and measures, values of the United States dollar at various rates in exchange, and ewts., &c., with their equivalents in pounds. It is evident that great labour and care have been bestowed on this work to render it a compendious and accurate Ready-Reckoner for almost every department of British Mercantile

life.

Proceedings of Societies.

SCOTTISH SHIPBUILDERS' ASSOCIATION. At the last meeting of this Society, a long and important paper was read by Mr. J. G. Lawrie "On Lloyd's Rules for Iron Ships, and their Improvement." We can give only the substance of it. The object of this paper is to examine, first, the strains to which a ship ashore is exposed, and the ratio in which the seantlings for ships of different tonnage should be proportioned to meet these strains, next, the strains to which a ship afloat is exposed, and the corre sponding ratio in which the scantlings should be proportioned. Then the propriety of various changes that have been proposed in the mode of building ships, as well as the effect of using improved material. 1. Ashore Strain.-Pursuing the investigations of Mr. Fairbairn and Mr. Mansel, regarding the strength of ships, on the supposition that they are beams or girders, Mr. Lawrie arrives at this conclusion-" If ships of different tonnage be of the same proportion of length, breadth, and depth, of the same or similar form, and if the iron be similarly distributed, the section of iron in the midship section of the ship, forming the longitudinal fastening, must be exactly proportional to the tonnage, so that the ship may possess equal strength when ashore and placed as a bridge or a beam in the manner already explained. Similarly, it appears, that on the same conditions the united cross section of the floors, and angle iron of the floors, forming the transverse fastening of the ship, must also be proportional to the tonnage. Hence, if the scantlings be increased for different tonnages in the manner contemplated, or, in other words, be adapted to "ashore strain," the quantity of material increases as the ship becomes larger, in a greater ratio than the tonnage, and eventually the whole displacement is necessary to float the ship without cargo.

2. Afloat Strain.-The more considerable strains which a ship experiences in a gale of wind are of different characters, and vary in ships of different tonnage according to different laws or ratios. Those strains which are due to the rising or falling of the ship with the waves-the bending strain lengthwise, due to the original inequality of the displacement with the weight of the ship-those due to the form of the wave, and to the consumption of coal, &c., in steamers,-vary in a manner that prescribes scantlings which give a midship section of iron proportional to the tonnage of the ship or to the cube of the length, breadth, or depth. Those strains, on the other hand, which are due to seas striking the sides of the ship, and to the effect of the masts and sails, vary so as to dictate scantlings proportional to the length, breadth, or depth, giving a midship section of iron proportional to the squares of the length, breadth, or depth. To meet these two classes of strains, which are of different character, and vary according to different laws, the scantlings require to be varied for ships of different tonnage in accordance neither with the one law nor with the other, but in a manner diffe

rent from both. It appears most judicious, if the scantlings are proportioned to "afloat strain," to vary the whole of the longitudinal fastening, with the exception of the upper deck stringers, in proportion to the length, or breadth, or depth of the ship,-to vary the area or section of the upper deck stringers in proportion to the cube of the length, or breadth, or depth-to vary the thickness of the transverse fastening in proportion to the square root of the tonnage, giving a midship section of the transverse fastening in proportion to the square and cube roots of the tonnage multiplied together.

are placed at intervals of 60 feet. There are decks with beams extending from side to side of the ship; also decks extending from the side of the ship to the fore and aft bulkheads; and the deck at the top of the bulkheads. Besides these decks there are others at both ends of the ship, beyond the ends of the fore and aft bulkheads. The upper deck is cellular, the cells being 1 foot 9 inches deep; the beams of the deck at the top of the bulkheads are of ordinary bulb iron, 9 inches deep; the beams of the upper deck, which extends from side to side of the ship, are 1 foot 9 inches deep, but are cut at the bulkheads; the Lloyd's scantlings are by no means widely different beams of the lower deck, which extend from side to side, are 2 feet 9 inches deep, and pass through the from the scauntlings proportioned to "afloat strain," except in very large ships, where the difference is of bulkheads. The bottom of the ship, to the height of some importance, but are widely different from scant- the last named deck, is double, the distance betwixt lings proportioned to "ashore strain." To proporthe skins being 2 feet 10 inches; between the outer tion the scantlings of ships, as if for a beam resting and inner skins there are the webs or ribs, which exon the centre, with either or both ends unsupported, tend longitudinally, and transverse webs. The cellu in the manner contemplated by Mr. Fairbairn, the lar deck extends 350 feet in the length of the ship, bottom and sides would be lighter considerably for and at intervals of 60 feet is tied across by cellular ships under 1,000 tons than at present, and the parts platforms 7 feet wide. All the bulkheads, both fore towards either end more tapered; but for small ships and aft and transverse, are stiffened by ribs 2 feet scantlings so proportioned would be perfectly inade- 6 inches wide. The thickness of the plates forming quate to encounter, not only the various afloat strains, the outer and inner skins is of an inch; the plates but also the various strains received in harbour, of the longitudinal and transverse ribs inch. The while, for ships above 1,000 tons, the scantlings of top and bottom of the cells of the cellular deck are the bottom and side plates would be greatly heavier 1 inch thick, being each formed of two thicknesses of than at present, and for all ships the scantlings of the-inch plate; the diaphragms of the cellular deck, ends would be insufficient, owing to the excessive taper. The changes proposed in the mode of building iron ships fall next to be considered.

3. It has been proposed that the frames of ships should be placed diagonally on the side, and that they should lie forward in the head on one side of the ship and aft on the other side. On consideration, however, it is apparent that the strength or tenacity of the upper deck stringer, the most heavily strained part of a ship, whether "afloat" or "ashore," is not affected by the position or inclination of the frames, and will therefore give way with the same amount of strain whether the frames be vertical or inclined. And similarly, it appears that the tenacity of other parts of the longitudinal fastenings is unaffected by the position of the frames. With the frames placed as proposed in this plan, the bulkheads are difficult to construct, the beams are troublesome, and what is more important, the quantity of iron in the frames is increased in the ratio of 1 to 2, if the angle is 45that is, the quantity of iron for the same strength is increased in the frames 12 per cent.

In a scheme somewhat analogous it has been proposed to place the deck beams diagonally across the ship, having the starboard ends of those of one dock forward, and the larboard ends of those of another deck.

It is difficult to see what object can have originated these ideas. With the beams arranged diagonally, every sea that strikes the ship exerts, with an enor mously increased leverage, a strain to start every rivet that passes through the skin plates and frames, and also causes an increased strain to start rivets in the seams of the plating near the beams. The stroke of a heavy sea upon the side of a ship supported in the best manner with beams in a perpendicular direc tion is sufficiently severe, without an artificial leverage introduced to increase the effect. Besides, as with angular frames so with angular beams, the weight of material in the beams, to preserve an equal strength of beam, is increased 42 per cent., if the angle of the beam is 45°, or 15 per cent. if the angle

is 30°.

It has been proposed to improve the keels of ships by cutting the frames and floors across on the middle line, and introducing a built keel. When it is cut across, as in this plan, it is impossible to restore the transverse strength equal to that possessed with floors and frames uncut, without a very considerable quantity of material on the top of the floors transversely. The strength of any fabric to resist bending up or down is measured by two elements, one being the quantity of material and the other the amount of compression or extension which that material would sustain in the bending of the fabric. In this ar rangement all the centre part of the deep plates forming the keel, all of it distant from the top or bottom of the keel, is compressed or extended exceedingly little, and in that proportion contributes exceedingly little to the strength of the keel. If the quantity of material in this keel was concentrated at the top and bottom edges, the strength would manifestly be largely increased.

The dimensions of the Great Eastern are:-Length between perpendiculars, 630 feet; breath of beam, 83 feet; depth of hold, 58 feet; tonnage, B. M., 23,0924. The construction is as follows:-The longitudinal bulkheads extend 350 feet, and are placed at a parallel width 36 feet. The transverse bulkheads

inch; the plates of all the bulkheads and stiffening webs, inch; the plates of the deck beams are inch, and of the deck beams in the lower deck from side to side, inch.

A ship of the same size as the Great Eastern, built in the usual manner, and with scantlings for the tonnage of 20,000 tons, according to the plan now proposed, would have frames placed 2 feet 6 inches asunder, extending, as usual, right across the ship, and formed of angle iron 13 x 8 x 1, with reversed angle iron 9 x 8 x 1; and floor plates 4 feet 10 inches deep x 1 inch in thickness. The beams would be placed 5 feet apart, by 20 inches deep x 1 thick, with 7 x 7 x 1 angle iron, on each side of the upper edge, and angle iron of proportional scantling on each side of the under edge, to form the bulb of beam iron. The upper deck stringer, part of which could be placed above the beam and part below, would be together with the angle iron in section, = 5 inches x 7 feet 6 inches x 4 inches x 2 feet 1 inch. Three box keelsons on the bottom would be used instead of an external solid keel, and two at the level of the orlop beams instead of the stringer plate for that deck.

By comparing the scantlings in these two cases, it appears that if the Great Eastern, the section of the outer and inner skin plates of the bottom, be added to the section of the longitudinal ribs and angle irons, the longitudinal fastening is 40 per cent. less in section than in the proposed ship; that the section of the cells forming the upper deck longitudinal fastening in the former is greater than in the latter, to the extent of 15 per cent.; that the section of the floors or transverse fastening in the former is only 1-10th of the section of the transverse fastening in the latter.

Those figures, and an examination of the kind of fastening in the two modes of building the ship, would make it appear that a ship built as now proposed, is stronger than if built as the Great Eastern. In the Great Eastern the transverse frames are cut across in no less than thirty-two places by the longitudinal ribs; and although at the intersections the transverse and longitudinal ribs are riveted together, it is impossible to restore the transverse frames to the strength they would possess if uncut; and in proportion as the riveting is increased to strengthen the transverse frames, in the same proportion is the strength of the longitudinal ribs destroyed. In the proposed vessel the transverse fastening or frames is kept clear of the longitudinal fastening, and the strength of each is not only maintained, but increased, by the arrangement of the connection. In the Great Eastern there are very few deck beams amidships, the cellular stringer on one side of the ship being connected to that on the other side only at intervals of about 60 feet, by platforms 7 feet wide; while in the other there are deck beams spaced at 5 feet. a ship is vertical the two sides are pressed together with a considerable pressure, being in the Great Eastern, for 350 feet amidsdips, upwards of 4,000 tons on each side; and when a ship is inclined or lying over, there is not only the same crushing pressure, but also, as has already been mentioned, a considerable angular or diagonal pressure, tending to open the angle formed by the side of the ship and beam at the windward side, and to close the angle at the lee side. In the Great Eastern this action will be so much the more severe, as the whole effect will take place at the small number of parts where the two

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