(For the Mechanics' Magazine.) Sir, - During my residence in the Western States of Amerca, I devoted some attention to fresh-water navigation, a subject which is very little known in this country. In the newspapers, we fre.. quently read accounts of the accidents produced by the bursting of the boilers of the Mississippi and Ohio steamers; and as often have these accidents, without any reason whatever, been attributed to the principle of the engines, all of them being high-pressure, though a few steamers are (or were) provided_with condensers on the English plan. I say, all the engines are high-pressure; for the average working pressure of the steam is 135 lbs. on the inch; though many of the boats work regularly with a higher pressure than that, and but few with a lower. This, I am informed, is the average pressure to which the safety-valves are loaded; though when an engine is working properly, it occasionally blows off a little steam. Engineers like to see a puff now and then from the safety-valve, as it proves that every thing is going on well, and that

the firemen are doing their duty. When racing the safety-valve is often loaded, or trod down, and the pressure is then unknown. I have seen tar and rosin thrown into the fire on these occasions; but though I have travelled many thousand miles in steamers on the great Western rivers, and made it a rule to inquire into all the accidents, explosions, &c. which occurred in the west for six years, I never knew of or heard of an accident to a boiler when racing; I also saw the answers sent by many of the steam-boat owners, captains, engineers, insurance agents, and so forth, to Mr Livingston's (late American Envoy to France,) queries, which were contained in a circular, requesting information on this subject, in hopes of his being able, when Secretary of State, to frame some law to prevent these accidents. All the answers contained similar statements, attributing every accident, with one exception, to the neglect of the engineer, in permitting the level of the water in the boilers to fall below the fire level, when the boat or boats were at rest. The exception occurred on board the Caledonia on her way from New Orleans. This explosion was attributed to the bottom of one of the boilers becoming red hot, from the immense quantity of clay which accumulated in them during their passage down the Ohio and Mississippi, and up the latter river, to a short distance of the mouth of the former. These rivers were very turbid, and such was the haste, that no delay occurred at New Orleans in discharging and taking in a fresh cargo, so there was no opportunity of clearing the boilers when the vessel was in that port. The person who put the new boiler in, assured me he felt quite certain that the accident occurred in this way.

I say that it is the general opinion, in which I concur, that the explosions and cases of collapse of flues, known to have occurred in these steamers, where the cause could be discovered, were traced to the engineer's permitting the water in the boiler to fall below the fire surface, when the vessel was at rest. Such rests are very frequent. They occur in putting passengers or freight ashore, or taking in passengers, freight, and fuel. The fire is kept up, though the engine is stopped; the steam passes off, and as the force-pump is not at work, the

water quietly boils away until its surface falls below the fire level. The belt of iron above the surface of the water, and under the highest fire level, becomes red hot, and continues so until the boat is moved by the engine being set to work. The boilers first obey the movement of the boat, and are carried forward, the water in them remaining at rest, until it is accumulated in those ends of the boilers in the direction of the steamer's stern. The mass of water is now driven forward in the form of a wave by its own gravity, and passing over a red-hot surface, is in part decomposed and flashed suddenly into steam of very great elasticity. The joints also get an oblique strain at the same moment, the hot lap in contact with the water being cooled and contracted suddenly, while the under lap exposed to the fire is still hot. This must act as a sudden blow across the rivets, which occurring exactly at the moment of the sudden strain from the increased steam and free hydrogen, is doubtless the cause of the explosion. It is unnecessary for me to add, that no species of valve or fusible plate can protect or prevent such accidents as these. Legal or penal enactments, it is to be feared, will be equally useless, for the engineers are not deterred by the fate which surely awaits them in case of an explosion. Men will idle, sleep, drink, and talk with passengers. I have spoken to officers of steamers, and though they all admit the absolute necessity of a change in the regulation of the engineers, yet none of them would adopt the following suggestions, though all admitted the absolute necessity of something being done. The reader will readily comprehend why the suggestions were not adopted, when he is informed of the order or discipline and duty of the officers of a great Western steamer, several of which are above 900 tons' measurement, and one, the Homer, above 1,000 tons.

The first officer in command is the captain. His duty is to see that every person in the vessel, except the engineer, is attentive to his duty. He may advise -that is all.

The pilot who navigates and actually steers the vessel. The wheel is never out of his hand, or his assistants, the whole time the vessel is in motion. He rings the bell for the engineer to get

the engine in motion (to go ahead), to invert the motion (to back her), or to diminish the speed, or to increase speed, or to throw one or both paddles out of geer, by means of a contrivance which I have only seen in the Western steamers. The pilot, too, has no control over the engines; he may complain of want of steam, or speed, to the captain, who may give the engineer some abuse, or report him to the owners, or in some cases dismiss him. It is an understood thing, that the pilot must not be interfered with by the captain, any more than the captain of a merchantman would be allowed to meddle with the sailing of a ship going into a harbour, after shipping a regular pilot.

The clerk is the captain's assistant. He takes his place in case of illness, death, or accident. His duty is to attend to the receipts and payments for freight; passage money; the landing and receiving of goods; the purchasing of wood for fuel; the ship's papers and accounts. He is also expected to mind that proper notice is given the pilot of the place to land, or take in, or put out passengers and freight, so that the vessel may be "rounded to" in safety, and brought alongside, or the boat rowed, as the case may be.

The mate attends to the crew on the forecastle, and as the fire-doors open on that part of the vessel, he has control over the firemen. The engineer may cominand them, but he generally gives the word to the mate or his deputy. The mate receives and stows the cargo; takes care that it is so arranged that the different parts are easily come at. He examines the pumps, the hold, and bottom of the vessel; he has the decks and roofs washed and swabbed down before sun-rise; he must also attend to live stock, and keep a look out for fire, particularly when cotton and other combustibles are above deck.

The crew are generally sailors who take a turn at fresh-water navigation for a season. Their duty is to attend to the mooring and unmooring of the steamer, parting the cargo, and so forth. They put passengers ashore in the boat.

The firemen are often slaves in the cotton boats, but in the upper boats they are generally Americans. Their duty is to feed the fires constantly, night and

day. They also assist in cleaning the boilers and in taking in wood.

The deck passengers assist in taking in wood at the different stages; and in case of the steamers taking the ground, they are expected to assist in getting her off. For these services an allowance is made them in their passagemoney.

The number of hands available in case of an emergency, is very great on the return trip from New Orleans of a large boat. The total number is sometimes about 1,000, and frequently above 500. It is quite a common occurrence for the captain to call the cabin passengers together after they have started, and their names, places of destination, &c. been entered, and request them to take into consideration the circumstances in which they are all placed, and the necessity of order and discipline being preserved, both in the cabin and steerage or upper deck. He concludes by moving, that three gentlemen be appointed by the cabin passengers from amongst themselves, to whom all quarrels and differences shall be submitted; these three to form a court for the trial of all offences which may occur on the voyage. The captain then retires, and the choice generally falls on persons who are well qualified for the task. The captain confirms all their decrees, and punishes by landing persons condemned, or puts them in irons, until he hands them over to the civil authorities at the port he is bound to. This court is extremely use ful. It affords the cabin passengers amusement, and keeps the deck passengers in order. Indeed, its influence is incalculable. I have known cases of murder, robbery, crim. con., libel, &c. to have been tried by them, and perfect satisfaction given to all parties. This court relieves the captain of much trouble; if complaints are made to him of any particular person, he brings the parties before the court, and leaves them until the judgment is pronounced, which he generally confirins.

On board every steamer there is a carpenter and assistant; in large vessels a. head cook and assistants, two or three stewards, and a woman in the ladies' cabin. In some there is a washerwoman, who assists in the ladies' cabin also.

The reader must now be aware of the immense number of human beings which

are congregated in the moving ark, and as, the steam-boilers are placed on the deck, an accident or explosion must do great mischief. Hence the great necessity of care and attention on the part of the engineer, whose room and workshop is generally close to the boiler, so that he is sure to be killed or scalded in case of an explosion.

After giving the subject of the explosions of the boilers of the Western boats every consideration, and talking over the matter with different intelligent captains, engineers, and engine-makers, I was led to suggest the propriety of furnishing each boat with a cistern to hold a supply of water for two hours. This cistern to open by a pipe into one of the boilers at the proper water level. The cistern to be placed above the boiler. It would then act like a bird-fountain; and when ever the water in the boiler fell below the level of the pipe, that instant the water from the cistern would flow into the boiler until the proper level was established, and so on until the reserve supply was used. The gauge to this cistern to be so placed that the pilot could see it before he rung the bell for the boat to go. on. I afterwards thought it better, because cheaper, to suggest the propriety of attaching two gauge-cocks to each of the side boilers by means of tubes cased in charcoal, which should be conveyed upwards to the steering-house, where they would be close to the pilot's hand; thus the pilot would be enabled to discover the level of the water in the boilers before he rung the bell, or the vessel was moved Finally, I suggested that one tube and gauge-cock might be taken from each side boiler at the lowest safe water level, and carried up to the steering-house, to be always examined by the pilot before he made the signal for starting.

In this simple manner a check would be established on the engineer, by a person of known character, one who must be always at his post, and always alive to his i duty, and, at the same time, much exposed to any casualty which should hap pen from the engineer's neglect, the pilot's station being immediately over the boiler..

The benefit of this arrangement was admitted, but nobody adopted it, though it would not have cost five dollars to make and secure the proper apparatus. The objection was more to the change of. responsibility than to the apparatus.

The pilots would not like it; as it was, they thought they had quite enough to attend to.

As to the reserve cistern, it would cost too much, and it would be so much dead freight. It might be of use, where idle or lazy engineers were employed, but at -other times it would be worse than useless. Under the circumstances, the parties entrusted thought it better to run all risks, and go on as before. Thus we see habits established and a mode of procedure confirmed in a few years; for it is only a few years since the first steamer floated on the Ohio, or any other Western river. The number now must amount to upwards of 300, and less than 400. Nearly all of these occasionally visit New Orleans.

I made a calculation from the tables in the insurance-offices, and think their number above 340. These boats are all built of wood. They are not coppered, for any kind of sheathing would be torn off by the drift wood, snags, and so forth. There was some expectation of iron boats being adopted when I left that part of America, but I have not been informed of any yet built.

If you think the subject worth public attention, I will continue it in my next, and give you details of the construction of engine, &c. &c.

Truly yours,

EDWARD TALEBOIS.

[We shall have much pleasure in laying a continuation of Mr. Talebois's interesting correspondence before our readers. Mr. T. alludes in a postscript to "an outline of the Huntsman" as accompanying his present paper, but this we have not received. If it has miscarried, we hope he will oblige us with another.-ED. M. M.]

LONDON AND GREENWICH RAILWAY.

Yesterday the experimental running of the train of engines and carriages commenced at Deptford about 3 o'clock, and continued until 5, to the great delight and satisfaction of the multitude present, among whom were several foreigners of distinction and members of the Society of Friends. The Royal William engine, which appeared to be the favourite, led off a train of eight elegant carriages, containing nearly 200 persons, in very gallant style, from the

High-street to the Grand Surrey Canal, at which place many gentlemen alighted to inspect the beautiful oblique elliptic arches over the canal. Every arrangement for the convenience and comfort of the visiters seemed to have been made, and the utmost order prevailed. We understand that it is the intention of the Directors to continue these trials every Thursday until the whole of the rails are laid, and the finishing touch given to the line to Bermondsey, which will be in a few weeks, when the travelling in earnest and for hire will begin.

THE PATENT LAW AMENDMENT ACT.

The challenge which we threw out in our last Number to Mr. Archibald Rosser, to give the name and title of the patent which he alleged, in his letter to the Times dated the 5th of October, had been actually amended under the new Act, and also to describe the form of proceeding which he averred had been agreed on by the Attorney-General and Solicitor-General, has remained, as we expected, unanswered. And for reason good-no such amended patent existed at the time "he wrote," and no such form of proceeding had been agreed on. That we

might be the better assured of these facts, we went on Saturday last (five days after the date of Mr. Rosser's letter) to the Inrolment-office, and there ascertained that there had not been at that time a single disclaimer or memorandum of alteration filed, or offered to be filed. We made inquiry, also, at the proper quarters as to the form of process alleged to have been agreed on, and found that that, too, was equally imaginary. We got a sight, however, of a paper headed

Proposed Form of Proceeding," the ink of which was hardly yet dry, and which was (we believe) on that day submitted for the first time to the AttorneyGeneral and Solicitor-General. We were wondering who the proposer might be, when a little bird whispered into our ear that the "Proposed Form" came from the very Mr. Archibald Rosser who had affirmed that all was agreed upon ten days before, and that it had been concocted between this person and a clerk of the clerk of the Clerk of the Patents-the same high functionary, we presume, who appears, from a notice in the corner of the Times devoted to correspondents, to

have sent to that journal an attestation of the truth of Mr. Rosser's most untrue story.

We shall make no comment on these facts, but leave them, and the conduct of Mr. Archibald Rosser's ally, to the impartial judgment of our readers.

NOTES AND NOTICES.

Calculating Machine. The Salopian Journal contains a letter from a Mr. Thomas Evans Jones, in which he says "I have invented a machine with which numeration, addition, subtraction, multiplication and division, simple and compound, including weights and measures, &c., may be worked by nine or twelve pupils in a class (without the aid of books or slates,) with the same figures, altering the sums at pleasure; by which means a very rapid improvement is effected in the scholar, and the labours of the teacher greatly diminished.”

Wooden Pavements.-We observe from the New York papers, that a trial is about to be made in that city of the plan of paving with wood followed in St. Petersburgh, and repeatedly recommended by us for adoption in the more retired parts of our own metropolis. A part of the Broadway has been selected for the purpose. "Each of the small blocks of wood is of hexagonal shape; the whole are fitted together and driven up tightly, by a long strip of timber near the gutter at the sides; and the interstices between the blocks to be well paved with tar or pitch."

Brussels Railway.-The projectors of this railway took credit for 100,000 passengers only, as the number that would avail themselves of it in travelling between this city and Antwerp; but although it has not been opened more than five months, the number already exceeds 200,000.-Brussels Paper.

Windmill Ship.-The Biblioteca Italiana mentions, that one Guiseppe Bruscetti, an engineer, has constructed a ship which is propelled in the manner of a windmill. "The vessel has two paddles like a steam-boat, and the mechanism of the windmill is so contrived, that if there is any wind at all, from whatever quarter it may blow, the vessel is propelled by the action of the sails, and may be steered in whatever direction is desired." We suspect that this is but an Italiau resuscitation of some of the many schemes of the same kind which have been broached in England-two or three of them in our own pages. If Signor Bruscetti will consult our 16th vol., p. 65, he will see what he has to expect, should he ever attempt to carry his ideas into practice on a large scale.

The most remarkable result of barometrical measurement was recently obtained, by Baron Von Humboldt showing that about 18,000 square leagues of the north-west of Asia, including the Caspian Sea and the Lake of Aral, are more than 320 feet below the level of the surface of the ocean in a state of mean equilibrium. This enornous basin is similar to some of those large cavities on the surface of the moon, and is attributed by Humboldt to the upheaving of the surrounding mountain chains of the Himalaya, of Kuen-Lun, of Thion Chan, to those of Armenia, of Erzerum, and of Caucasus, which, by the undermining of the country to so great an extent, caused it to settle below the usual level of the sea. The very contempiation of the destruction which would ensue from the bursting of any of those barriers which now shut out the sea, is fearful.-Mrs. Somerville.

The Greenwich Railway.-A report has been industriously circulated for gambling purposes during the present week, that the Greenwich Railway

7

Company are in want of from 100,0007. to 200,0007. over their estimate to complete their work; we are authorised to say, that this is altogether untrue, and that so far from it, there is more than probability that the work will be completed within the estimate, notwithstanding considerable expense has been incurred for works not included in the original estimate.

The Needle in Iron-Boats.-Captain Johnson, R. N., has been directed by the Lords of the Admiralty to proceed to Limerick, for the purpose of making certain experiments on the attraction of the needle on board the iron steam-boats in the Shannon. It appears that the compass has been found nearly useless in these vessels.-Times.

The Parliamentary trustees on the river Clyde have offered a premium of 100 guineas for the best practical mode of preventing accidents from the imperfect construction of steam-engine machinery. Another 100%. is to be divided amongst the unsuccessful candidates who invent something worthy of attention. Mining Journal.

The Eye, being a material organ, of course has a limit, beyond which it cannot see; but the range is greater than any length which we can determine; and we have an easy means within that range of finding the rate at which the action of light is propagated. We can observe the planet Jupiter in two different positions of the earth's orbit; in the one of which we are the whole diameter of the orbit of the earth, or about 199,000,000 of miles, nearer to Jupiter than in the other. We can also calculate the time at which the eclipses of Jupiter's moons begin and end; and this we can do, referring them to a common centre. Now it is found, by actual observation, that when the eclipse is observed from the longer distance, it happens about 16 min. 26 sec. later in time than when it is observed from the shorter distance. The part of the eclipse which is chosen for this purpose is the instant that the Moon emerges from the shadow of Jupiter, and it is evident that the above-mentioned minutes and seconds are the time that the light of the satellite requires to travel across the earth's orbit; and if we divide the diameter of the orbit by the seconds, we find that the propagation of light is at the rate of about 192,000 miles per second. We cannot accurately observe a much shorter time than the fifth of a second, and during that time light advances 38,500 miles, or rather more than equal to 1 times round the earth.-The Earth.

Communications received from Mr. Gray-R. S. -A Seeker after Knowledge-W. F. G. W.-D. M. -Mr. Mackintosh.

The Supplement to the last volume, containing title, index, &c. and portrait of Charles Vignoles, Esq., C. E., is just published, price 6d. Also, the volume complete, in boards, price 9s. 6d.

Patents taken out with economy and despatch; Specifications prepared or revised; Caveats entered; and generally every Branch of Patent Business promptly transacted. Drawings of Machinery also executed by skilful assistants, on the shortest notice."

LONDON: Published by J. CUNNINGHAM, at the Mechanics' Magazine Office, No. 6, Peterbo rough-court, between 135 and 136, Fleet-street. Agent for the American Edition, Mr. O. RICK, 12, Red Lion-square. Sold by G. G. BENNIS, 55, Rue Neuve, Saint Augustin, Paris. CUNNINGHAM and SALMON, Printers, Fleet-street.