The best constructed safety-valves, however, may get deranged from rust or other causes, and by remaining closed after the steam has attained the pressure at which it should be permitted to escape, may fail in performing their duty. A mercurial gauge is generally applied to the boiler, by an examination of which the engineer may at any moment ascertain the expansive power of the steam. locked up so as to be inaccessible to the engineers,, occur to low-pressure and high-pressure boilers. no danger is to be apprehended from their being Some engines have self-acting pumps for the supply overloaded, a practice too frequently resorted to by of water, and in others the injection-cock is under the ignorant men to whom the management of steam-the control of the engineer, who by opening or shutengines is occasionally intrusted. ting it, regulates the supply. The latter plan is adopted in all locomotive engines, and in most of the American steamboats. It is of the greatest consequence that the water-pump should be so arranged as to work while the engine is at rest. The steamboats on the eastern part of the United States, are not so constructed; but in the steamboats on the Mississippi and the St. Lawrence, as formerly noticed, I found apparatus for effecting this important "The safety-valves and steamgauge perform a object. A gauge is applied to almost every boiler, most important office, and operate chiefly when the for indicating the height at which the water stands engine ceases to work, as, for example, when a in its interiour, and if this is carefully observed, and steamer stops to land passengers. The volume of tried from time to time by the engineer, it forms a vapour which is no longer withdrawn for the supply great means of preventing accident. Some ingeniof the engine, is permitted to escape by the opening ous applications have been proposed to render the of the valves; while the steamgauge, by indicating safety of the boiler less dependant on the attention any increase of pressure, gives timely warning of of the workmen. One of these is a valve of larger danger, and calls the attention of those in charge to dimensions than the common safety-valve, which is such measures as may arrest the too rapid accumula- intended to be acted on by the expansive force of a tion of steam within the boiler. Thus far the safety-rod of iron, when heated beyond a certain temperavalves and steamguage have the effect of insuring ture. The introduction of plates into the sides of the safety of the boiler, but unfortunately they have the boiler, composed of an easily fusible metal, no control over the accidents arising from a defi- which would melt before the contained steam had ciency in the supply of water, to which circumstance attained a dangerously high temperature, and form almost all the explosions which now take place may large vents for its escape, is another method not unbe traced. worthy of attention. "The heat to which the flues and bottom of a "The collapse of the large boilers of weak consteamboiler are exposed may be very intense, but struction, which are sometimes employed for genethe metal of which they are formed will preserve rating low-pressure steam, is another casualty to a comparatively low degree of temperature, so long which steam-vessels are liable. It is occasioned by as its interiour surface is kept in contact with the the fire getting low, and the surface of the boiler bewater. If the level of the water be permitted to coming cool. This produces condensation of the sink, however, so as to uncover or lay bare part of steam, and the formation of a partial vacuum in the the flues or bottom, the action of the fire immedi- interiour of the boiler, the form of which is geneately renders the parts so exposed red hot. When rally so ill calculated for resisting external pressure, this state of things occurs, a boiler, as we shall that it yields to the weight of the atmosphere. A presently see, is placed in a most critical situation. spring valve so constructed as to be opened by exDeficiency of water may occur when a vessel is internal pressure alone, is occasionally applied in this motion, from derangement of the apparatus for country. When a vacuum is formed in the boiler, its supply, but it is most apt to arise when a vessel the valve is opened by the weight of the atmosphere stops for the purpose of taking in goods or landing passengers. On such occasions the working of the engine is stopped, and at the same time the pump for supplying the boiler with water must cease to act. Meanwhile, the fire is kept briskly burning, and if the stoppage is of long duration, the level of the water, from the evaporation which is going on, falls considerably, and occasionally to such an extent that the flues become exposed and are quickly rendered red hot. When the vessel is about to proceed on her voyage the engine is set in motion, and the pump, which has till then remained inactive, injects heated water into the boiler. This water comes in contact with the portions of its surface which have been un-rest." covered and rendered red hot, and is instantaneously converted into vapour. So rapid is the change, resembling in effect the ignition of gunpowder, that the safety-valves, in most instances, are too small to give vent to the immense volume of vapour which is suddenly created, and an explosion of the boiler is the unavoidable consequence. “A proper uninterrupted supply of water is the only safeguard against the occurrence of such explosions, which, from their nature, are equally apt to on its exteriour surface, and the air rushing in, restores the equilibrium, and insures the safety of the boiler. The exposed situation in which the boilers of all the American steamboats are placed, renders them very liable to collapse, which has been of very frequent occurrence, and has on some occasions been attended with serious consequences. "Of the several adaptations for reducing the chances of accident which I have mentioned, I found in use in the American steamboats the single safety-valve, the steam-gauge, and the watergague, and in a few vessels the apparatus for conuinuing the supply of water while the vessel is at The following from the pen of W. C. Redfield, Esq., of New York, is taken from the November number of the Knickerbocker, there published under the head of "English and American Steamvessels." The article was written to correct some errours in regard to American steamers which have found their way into the English journals, and as it suits our purpose admirably, we quote it entire. "The London Nautical Magazine' for August, | architecture. Thus it happens, too, with his steamers, contains an article on American Steamers,' which owing in part to the imperfections of their models or comprises a tabular description of some of the steam- construction, and the comparative inefficiency of boats in the New York waters.' This table appears their engines, that he still finds it expedient to emto have been furnished to the editor by an American ploy canvass, in aid of steam in his home navigation; correspondent, and though not entirely correct, is a practice which, in a steamer of proper efficiency, highly valuable for the information which it embo- is worse than useless, except perhaps on sea voyages. dies, and is therefore presented to the readers on an "There is, however, a' genus' of American steamadjoining page. boats, of which we are not so proud, and which unfortunately has furnished material to the editor of the Nautical' and other foreign writers, for most of their witticisms upon American steam navigation. This genus, whose habitât is chiefly on the Ohio and Mississippi rivers, has also contributed much to unsettle the publick mind, and to impair the just confidence which has hitherto been placed in the skill and science of American artisans and engineers; and which has likewise been the means of fastening upon our invaluable steam marine a legislative incubus, which bids fair to secure to the steamers of Britain the most valuable portion of our intercourse with the parent country. The sprightly and somewhat ironical article which the editor of the Nautical' has appended to this table, appears to be founded mainly on the loose and often discordant statements which appear from time to time in our newspapers. Of the numerous errours and false assumptions found in this paper, not the least is that of the supposed current of the Hudson, which is assumed to be of the moderate uniform rate of three miles per hour.' This current is allowed for, in a passage from New York to Albany, against the stream, whereas, the Hudson, being for the most part a narrow estuary, has no stream or current, except in case of freshets, for a few miles on the upper portion of the route, but exhibits a reciprocal course of ebb and flood tide, the average rate of which, for the entire distance, does not exceed one mile per hour. A fast steamer leaving New York on the flood tide, often carries it to Albany without change, from which may be derived an advantage equal to about ten miles in a passage. The ebb tide is in like manner often carried from New York to Albany, with a disadvantage proportionally greater, because encountered for a more lengthened period. The passage from Albany to New York, on the contrary, has this peculiarity, that the tides are always changed from ebb to flood, and vice versa, once in about three hours; so that a nearly equal portion of favourable and opposing tide must always be had in descending the Hudson; except that the ratio of opposing tide usually predominates, for the reason above given. "In the last remark here appended, there is more truth than poetry; and John Bull, it appears, is just obtaining knowledge of this to him unknown and hitherto unrivalled genus' of American steamboats. In regard to beauty of model, we can inform the editor of the Nautical' that Jonathan has been long at school, where he has learned pretty thoroughly the art of adapting means to ends, in the most direct and efficient manner. It is thus that he has learned to discard his former heir-loom notions of taste and beauty, and he no longer considers obsolete forms and appendages, which are in themselves useless or injurious, as being essential to symmetry and beauty in a river-going steamer. But John Bull has been so long accustomed to straitsides and bulwarks, quarter galleries and cutwater, the latter surmounted by bowsprit and figure-head, that is difficult for him to imagine any other standard of beauty in naval Omitted here for want of room. "Ours is a reading publick, while the writers on steam or steam navigation are almost exclusively English, and give currency to English views and opinions, whether the same be sound or practically obsolete. This tendency in our literature is unwittingly abetted by a great portion of the American press, the conductors of which are not sufficiently conversant with the facts and principles on which alone a correct estimate can be founded; while American engineers are better employed than in sketching the present state of their art, or in writing the chronicles of their own labours and achievements, which latter have a brighter and more enduring record in their results, and in the changes which they have so rapidly wrought upon the face of nature, and of human society. "It seems hardly to be known, at the present time, even in our own country, that a proper sea-going steamship, well adapted to the navigation of the Atlantic, was built and fitted out at New York full seventeen years ago, when the art of steam navigation in Europe was in its very infancy. This steamship, the Robert Fulton, made a number of voyages to Havana and New Orleans, but owing to the embarrassments of her owner, was dismantled, and sold in another country. This vessel was designed and built by that celebrated shipwright, the late Henry Eckford, for David Dunham, Esq., since deceased, and is now a ship-of-war, mounting twenty-six guns; and remarkable for her sailing qualities; having for several years past been attached to the Brazilian navy. This ship, if propelled by a modern York' engine, or with the portion of steam power which is now used in the best British steamships, would, even now, prove a successful rival to the Great Western; at least for any length of passage for which her structure was designed. New "Of the practicability of transatlantick navigation by steam power alone, American engineers have, for several years, been fully sensible. Of the probability of obtaining a remuneration proportioned to the outlay, however, great doubts have always been entertained. But should the sound practical talent of our countrymen be brought to bear properly upon this enterprise, a degree of surety and despatch which has not been realized, is sure to be attained.. THE GREAT WESTERN. Whether such an attempt be justifiable at this time, the Great Western's hold is twenty-three feet. The in view of the false position in which the American boilers and steam chests occupy the whole space from merchants and engineers have been placed by the the platform to the deck, they are four in number, recent investments of British capital in ocean steam-in two compartments, each boiler having a clear pasers, and by the unwise legislation of our own gov-sage all round it. There is fitted to each a change ernment, is a question admitting of more doubt. water-pump, through which at every stroke of the This remark is applied to the new steamboat law, engine a portion of water is drawn out from the more especially to that odious provision, which bottom, in quantity about one half that evaporated in makes the owners of American steamvessels liable, the production of steam, the whole of which is, of in case of accident, for all the property on board course, supplied with new seawater, but instead of their vessels, in violation of the first principles of reaching the boilers in a cold state, it acquires an justice, which deem a man innocent till he is proved additional temperature of about seventy degrees, by guilty." passing through a system of tubes, around which the hot water flows in its passage to the change pump; the water from the boiler is thus cooled down in the same degree, previous to its being dis"Toward the latter end of 1835, a company was charged overboard. The boilers are each furnished formed in London, called the British and American, with the common blow-off-cocks, which may be which proposed to lay down several steamers of used in case of need, but with the changing pumps large dimensions, to run alternately between London the operation of blowing off is not resorted to, conand Liverpool and New York. Previously, howev-sequently the steam and the state of the fires are er, to this, and while the Great Western Railway much more uniform. subscript ion efforts were on foot in Bristol, the grand object of making it an outpost to the metropolis for vessels of all descriptions trading on or through the Atlantick, was never lost sight of. The appearance of the Prospectus of the British and American Com-Length between the Perpendiculars Length of Keel pany brought matters to a point, and in November, Breadth in clear of Paddle-Wheels 1835, a party of gentlemen connected with the Rail- Breadth over Paddle-Boxes way (among whom were their celebrated engineer, Tunnage by Measurement Depth of Hold Mr. BRUNEL, and Mr. GUPPY,) after a good deal of Length of after Saloon Deck discussion on the feasibility of such an experiment, Length of after Lower Deck put down their names as ready to take shares in the Length of fore Cabin Deck Length of Engine-Room event of due encouragement being given in Bristol. It was some time in October, 1835, that Mr. GUPPY and Mr. BRUNEL consulted, and fairly enlisted the writer in the cause as a practical nautical man, ac- Weight of Engines Wheels, &c. quainted in his particular line with the full advan-Water to each 20 tuns Weight of Boilers tages of Bristol's position. and DIMENSIONS OF STEAMSHIP GREAT WESTERN. Length from forepart of Figure-Head to afterpart of Taffrail DIMENSIONS OF ENGINES, &c. Diameter of Cylinder Diameter of Wheel Length of Floats Number of ditto "The sternpost of its steamship, the Great Western, was raised on the twenty-eighth July, 1836, she was launched on the nineteenth July, 1837, proceeded on her way to London on the eighteenth August, and arrived in the river on the twentysecond of the same month, after a remarkable passage under canvass four fifths of the distance, hav- At ing left the steamer, a fast one, which was to have attended her, behind. Her first trial down the river was made on the twenty-fourth March, her second on the twenty-eighth March, in both of which she beat two of the fastest Gravesend boats. She eventually sailed on the thirty-first March, and arrived in King-road on the second of April, whence she started on her first voyage to New York on the eighth of the same month, and arrived out on the twentythird. "The boilers of the Great Western are peculiarly constructed, having in height or depth that capacity for generating steam which has been hitherto obtained in lateral space. Originally it was settled that there should be two sets of boilers and two chimneys, one set before and one abaft the machinery, but it was thought that the after boilers took off too much space from the saloon, and moreover would be likely to increase the temperature of the accommodations more than would be desirable in warm weather. It was, consequently, arranged that they should all be placed forward, or before the machinery. The depth of Ft. in. 236 212 205 35 59 23 1340 75 73 59 72 68046200000 No. 3, of Ditto 8 Ditto Tuns. cwt. qrs. lbs. 68 Draught of water at launching 694 10 0 0 12 1202 7968 221 19 71 5 10 Oak Timber 16592 a 58 Weight of Hull, Masts, Rigging, &c. 0 12 2 10 1 15 15 40 850 400 80 2372 0 WESTERN STEAMBOATS. several bars or plates laid or "piled" on each other, and welded or united by being passed, at a high THE following engraving is a fair representation of a heat, between rollers. Iron thus united is rather solWestern Steamboat, and as most of our readers are fami- dered by intervening layers of cast iron than actually liar with their construction, operations, &c. we shall not welded, as it is when it is struck by the hammer, detail these, but give in this connection some interesting and the fused portion, having the quality of cast iron facts and useful information taken from Dr. Locke's Re-made to spurt out, till the tough, perfect metal, is port on Explosions, and especially on the awful explo- brought into union. The several layers of the frag sion of the Moselle. Dr. Locke says ments of the boilers were evidently distinct, and in- In discharge of the duties imposed upon me with reference to the explosion of the Steamboat Moselle, I proceeded on the morning of the 27th of April, in company with one of our most intelligent and experienced engine builders, Mr. Tift, to the place of the disaster. The first point to which Mr. Tift drew my attention, was to the fact, that leaden collets, called grummets, which lie under the heads of the bolts connecting the boilers with each other, at OF THE WORKMANSHIP OF THE BOILERS. the place where the water communicates from one fully evident that the boilers had been faithfully put to the other, were not melted. These leaden col- together; for they were torn not in the seams merelars are inside of the boilers, and at a part exposed ly, but frequently through the solid sheets, the lapoutwardly to the fire, and at the same time so near ping and rivetting being quite a compensation for the top of the water as to be first exposed to great the weakness occasioned by the rivet holes. heat when the water should become too low; lower OF THE FORCE OF THE EXPLOSION. Of the imhowever than the tops of the flues. It is true there mense force exerted in this explosion, there is abunis a mass of metal forming the "chock joint" imme- dant evidence: still in this extraordinary occurrence diately outside of the leaden collars, which being in the history of steam, I deem it important to be exposed to the fire, must ordinarily be rather hotter than other parts, as it can neither lose heat by exposed surface, nor by an extensive contact with water. In a very sudden rise of temperature of the boiler, it would, by its mass, be a little tardy in acquiring the equilibrium of heat. The fact that the lead was not melted was fully ascertained in the fragments of the boilers, of about 50 to 60 square feet lying part of the way up the bank, opposite the place of explosion. This establishes the point, that in this individual boiler at least, the heat was below that of the melting of lead, which is six hundred and twelve degrees of Fahrenheit's scale, and quite below redness. Mr. Tift and myself examined all of the fragments, in which we could discover no evidence of a very high heat. particular in noting the facts, and for that purpose I have made some measurements and calculations. The boat was one hundred and sixteen feet from the water's edge, one hundred and ninety-two from the top of the bank, which was forty-three feet in perpendicular height above the water. The situations of projected bodies ascertained were as follows: Part of the body of a man thrown nearly horizontally into a skiff at the water's edge one hundred and sixteen feet. The body of the captain thrown nearly to the top of the bank, two hundred feet. The body of a man thrown through the roof of a house at the distance of two hundred and twelve feet and fifty-nine feet in height above the water's edge. A portion of the boiler, containing about sixty square feet and weighing about four hundred and fifty OF THE BOILER IRON. The iron of which the pounds, thrown one hundred and seventy feet and boilers were made, was one sixth of an inch thick,* about two thirds of the way up the bank. A second and to use Mr. Tift's expression "of as good qua- portion of the boiler of about thirty-five square feet, lity as modern boiler iron is generally." I am inform- and weighing about two hundred and forty-five ed by the manufacturers of the boilers, that the iron pounds, thrown four hundred and fifty feet on the was from the Sligo works in Pennsylvania, which have hill side, and seventy feet in altitude. A third pora good reputation. I do not censure the manufactu- tion of the boiler twenty-one square feet, one hunrers, but the custom which demands cheap boiler iron, dred and forty-seven pounds, thrown three hundred and excludes all other but rolled iron from the mar- and thirty-three feet into a tan-yard. A fourth porket. In manufacturing rolled iron, more cast iron tion of forty-eight square feet, and weighing three can be "run in" than it would be possible to work hundred and thirty-six pounds, thrown four hundred under the hammer, and there is a temptation to do and eighty feet into the garret of a back-shop of a this where the workmen are paid by the pound for tan-yard; having broken down the roof and driven the products of their labor. A cent or two in a out the gable end. The last portion must have been pound, a few dollars in a suit of boilers, would thrown to a very great height, as it had entered the enable the manufacturers to furnish forged instead roof at an angle of at least sixty degrees. A fifth of rolled iron. Perhaps this would be of little use, portion weighing two hundred and thirty-six pounds, for in the present unmeasured mode of using steam, went obliquely up the river eight hundred feet, and the pressure would constantly be urged close upon passing over the houses landed on the sidewalk, the the heels of danger. Boiler iron was formerly made bricks of which had been broken and driven deeply of solid masses called "slabs," welded by the ham-into the ground by it. This portion had encountered It is now made of "piled iron," that is of some individual in its course, as it came stained with blood. Such was the situation of the houses that it must have fallen at an angle as high as forty-five mers. * Three sixteenths in parts which had not been stretched. VOL. IV.-20 |