we have on record several accounts within a few years, and one very recently, of a still more awful and distressing nature. I have reference to the burning of a boat at sea, where the passengers and crew have no alternative, but must either burn or drown.

I do not now recollect having read any efficient mode proposed for extinguishing fire on board a boat, nor any other theory recommended than the ordinary mode with buckets and a fire engine.

Believing that there is always ready at hand and available, with proper fixtures, in every steamboat, an agent much more efficient than water and an ordinary engine to extinguish fire, I deem it a duty to make the suggestion, that others who may be disposed, and have better means than I can command, may try experiments upon it, and test the utility of the theory. From the few imperfect experiments my means have permitted, I am of opinion, that steam is far preferable to water to extinguish fire. For steam can be made to enter every apartment, birth, and crevice, even where water would not possibly be thrown, and being lighter than air it keeps the space filled instead of falling to the bottom as water would do, and can be as effective on the under side of a ceiling, deck, or floor as it would be on the top, and even more so.

The first that I ever noticed of the effect of steam upon flame was several years since, by carrying a lighted lamp into a room in a dye-house that was filled with steamn, and the light was instantly extinguished.

Again, when the steam was issuing from the nose of a teakettle, I have taken a bright coal of fire and held it in the steam, and the fire was quenched in as short a time as if it had been immersed in water, and as effectually through the coal.

Now if the theory be true (which, I confess, needs further experiment and stronger proof) a comparatively trifling expense may furnish every steamboat with certain and available means of readily extinguishing a fire, if it should take in the woodwork of the boat, or in the freight, either on or under deck.

I would propose the following mode of operation. Let a pipe, say a gas pipe, or any other that shall be of strength sufficient to bear the pressure of the steam, be connected with the boiler, either directly or indirectly, at pleasure, and be carried to every apartment in the boat. And in as many places as may be thought expedient, insert stopcocks of such construction that they can be readily and easily opened at any time and by any per

son.

In case of a fire in any apartment the occupants would of course leave the apartment as soon as possible, and when the apartment should be vacated, let the stopcocks be opened, and force in as much steam as would be practicable. Under deck, and in a close apartment, it would have a double advantage over water, for it would, in a great measure, exclude the air from feeding the flame, at the same time it produced an effect by its moisture, but the greatest effect would undoubtedly be produced by the excluding of

the air.

In addition to the foregoing, I would attach pipes and carry them on each side of the engine, fore and aft, upon the deck some thirty or forty feet, and at the terminations I would affix "gooseneck joints," and to these attach several lengths of pipe in joints of six or eight feet, and then another "gooseneck" and to this attach a directing and discharging pipe of about the same length as the other joints, all the connexions to be made with screw joints, or couplings.

The two goosenecks would enable the man having charge of the pipe to convey and use the steam on any part of the deck, with nearly as great facility as water would be conveyed and used with a hose: and, if necessary, any number of goosenecks may be used.

To enable the men to handle and use the pipes without burning their hands, let some two or three feet of each joint of pipe be incased in, or near, the middle, with a tin or sheet brass cylinder (brass is preferable,) one inch, more or less, at pleasure, greater than the steam pipes, and fill the space between the two pipes with pulverized charcoal, pipe clay, or soapstone dust, and outside of the exterior cylinder wind on some two or three thicknesses of woolen cloth, and this will fully protect the hands of the men in moving and directing the pipes.

It is thought that this mode of extinguishing a fire in a boat may be more effective than a fire engine, and may always be available at the moment it may be needed, whereas, with a fire engine, there must always be a delay, and frequently, perhaps generally, much difficulty in supplying it with water and in getting it into action, and more difficulty, in the terror and confusion in getting hands to work it; and these unavoidable difficulties, it is presumed, would, in most instances, let the fire get such headway that no power on earth could arrest its progress; and inevitable destruction is the consequence.

In any situation, a single bucket of water when a fire first takes, is of more effect than an ocean after the building is enveloped in flames. And on board a boat, especially, it is necessary to stop the progress of a fire immediately and with the least possible delay, for if the wind did not blow, the motion of the boat would produce a current of air sufficient to kindle a fire rapidly.

In general it would be favourable, in case of a fire, to run the boat directly before the wind, and this would, in a measure, neutralize its effect; but circumstances might alter the case in this respect.

As too much precaution, to preserve and render life and property safe, cannot be used, whether philantrophic motives, or those arising from self interest on the part of steamboat owners, be consulted, every boat should be well and constantly furnished with every possible means of safety or escape in case of accidents of any kind.

For one such catastrophe as that of the Lexington, is enough to deter thousands who would otherwise patronize steamboats with perfect confidence, from risking their lives and property on board a boat, for years. And unless some sure measures can be adopted and put in general use to render safety more certain to the public than has been the case, in very many instances, every year since steam got into general use as a motive power; this mode of conveyance and travelling ought to be totally abandoned.

But it is thought, by not a few, that most of the accidents are chargeable, in a very great degree, to neglect of duty and proper precaution, and to the want of preventive means on the part of those who own, as well as of those whose business it is to manage steamboats, and that it is fully practicable to render them as safe as any other mode of travelling.

I am not fully confident that there is any value in my hints respecting extinguishing fire by steam; but trust the reader will not impugn my motives even if he shall feel inclined to reject my theory as worthless.

If it have no other value than to draw from other and more ingenious minds some further and better views on the subject that may ultimately lead to the adoption of better modes to ensure safety, I shall feel fully compensated and highly gratified.

FOR THE JOURNAL OF THE FRANKLIN INSTITUTE.

Description of an improvement on the Bridge patented by ITHEIL TOWNE, Esq., the term of which patent has expired. By ITHAMAR A. BEARD, Civil Engineer.

Elevation.

The Improvement consists in the Upright Plank, and the Iron Bolts. The Bolts are marked with a full dot (.) The Treenails marked with an open dot (0)

3

+

Scale, twelve feet to an inch.

In 1836 I was requested to advise the best construction for a bridge to be erected over a branch of the Androscoggin river, at Brunswick, Maine, from the main land to an island.

Accordingly, I recommended Mr. Towne's bridge; and in making a model for the purpose, it occurred to me that a great addition might be made to the strength and durability of the bridge by the addition of a pair of upright planks (one on each side of the X work;) over one half the intersections, these planks to stand perpendicular like posts, and the treenails or bolts to pass through and connect the work and the uprights at each crossing.

My object and intentions were to prevent, in the greatest possible degree, the depression of the bridge, and, on trial, I found my expectations fully realized.

This bridge is 101 feet long, in a single span, and is built with a single travel only, twelve feet wide in the clear, and the travel of the bridge is arched, or crowned, sixteen inches in the centre above a level with the ends.

For the better convenience of drafting I have made the accompanying plans level from end to end, and in fact, in a bridge of this structure I cannot see that any benefit or advantage is derived by arching.

In this bridge, instead of the ordinary treenails, the principal intersections are firmly secured with bolts made of one and a quarter inch round iron, (Bank's best,) with cast iron washers, six inches in diameter, under the heads and nuts; a single bolt being used at each intersection.

There is a vast advantage in using the bolts, with heads and nuts, over the treenails, for, it not only holds the work together more firmly at first, but it likewise furnishes the means of keeping it always firm and close, for as the woodwork shrinks by seasoning or age, as is invariably the case, even if tolerably seasoned when worked, by turning up the nuts upon the screws occasionally, it may always be kept as compact as when first built.

Another advantage is, that the bolts need not be half so large as the treenails, and fewer in number are required, which very much saves the strength of the plank through which they are inserted.

The cost of building one of these bridges with bolts instead of treenails will be somewhat greater, but for a term of twenty or thirty years, I am fully of opinion that a bridge may be supported with less expense than if built wholly with treenails.

The bridge herein described was built by Capt. James Derby who now owns the Island and Mills thereon, and the work was most thoroughly put together in every part. The using of bolts instead of treenails was his suggestion.

After the bridge was completed, and before the trussels on which it was built were taken out, I set my levelling instrument and took the elevation of the travel of the bridge in the centre, and again after the trussels were removed, and it settled seven-tenths of an inch only.

This bridge has been in constant use ever since it was built, for teaming over with heavy loads of lumber from the mills on the Island, and it now stands as perfectly firm, true, and straight as it did when first completed.

To give a more clear idea of the cost of a bridge so constructed, I will insert the number of pieces and dimensions of all the materials of which this bridge is constructed, and also the cost for materials and labour as nearly as I can obtain them.

60 Do.

7 feet long, 6 by 4 inches.

840

Planking of the travel, 101 feet long 12 feet wide S inches thick 3636

Plank and Timber, in board measure,

28,006 Making allowance for waste, say 30,000 feet, worth here, at that time, $15 per thousand.

All the timber of this bridge is white pine.

The travel of this bridge is laid with the length of the plank lengthwise of the bridge. I do not think the plank will be so durable laid in this way as they would be if laid crosswise of the bridge, especially for heavy loads, and if planked crosswise a set of stringers must be laid on the crossills; say 5 stringers, 101 feet long 9 by 6 inches-2272 feet.

Taking the lumber of this bridge as it is 30,000, a $15 per thousand $450 00 632 cast iron washers, 3 pounds each, 2054 pounds a 5 cts.

504 Bolts 24 inches long weighing 2600 pounds.

34

66

12 Estimation for heads, nuts and waste 400

102 70

Say 3000 a 10 c. including making 300 00 The labour was done by hands hired by the day, at an average of about $1 50 each per day, board included, and cost as nearly as can be estimated, about

Equal to twelve dollars a foot in length very nearly.

375 00

$1227 70

It is estimated that a bridge with two travels, fifteen feet wide each, with two sidewalks outside of the work, and without a roof, may be built for twenty dollars a foot in length; timber and labour being at the same value as above rated.

To this must be added the cost of abutments and piers and of a roof if the bridge is to be covered.

There are no bridges in this section of country that stand so well and so durable as the "Town Bridge," and it is getting into general use. Brunswick, Maine, March 27, 1840.

Hydraulic Works at Algiers. By M. POIREL, Engineer of Bridges and

Roads.

[Translated from the Annales des Ponts et Chaussees by W. H. Emory, Jr., U. S. Topl. Engrs.]

The port of Algiers was established as far back as the year 1530, by Cheredin, brother of Barbarossa. Having made himself master of a little island, in front of the city, which the Spaniards had fortified, he resolved, in order to secure it, and at the same time to make, at Algiers, a harbour that would afford protection from the winds and from the swell of the sea, to unite it to the town by means of a jetty. This is called the Cheredin jetty, and is two hundred and twenty-three yards long and one hundred and twenty-seven yards wide. Its direction is nearly east north-east; or west southwest.

Besides the Cheredin jetty, another has been built on the prolongation of the island, which protects the harbour from easterly winds, and is called the mole. It is one hundred and seventy-four yards long, and forty-five yards in its greatest width. This mole runs north-east and south-west. These two