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"What is your opinion of this mode, which applies to the general form as well as to the other form?

"I am, dear Sir, &c. "J. COCKLE, Esq., &c., &c."

I forget the precise nature of my answer, but the elegance and beauty of the method would obviously admit of but one reply to the inquiry which DR. RUTHERFORD did me the high honour to address to me. If I recollect right, my first impression was that, scientifically speaking, its classification would be somewhere among the methods of BEZOUT. By the aid of the method of LAGRANGE We should, of course, have no difficulty in tracing it to that common source from which all solutions diverge. Its relation to LAGRANGE's process will be best exhibited by comparing it with my own. This may be done by an easy transformation; for, adopting the notation of p. 330, of vol. liii., of this Magazine, the equation (2) of p. 124, ib., becomes, on substituting for y,

{A(x-2) + B}3 - D3 (x-2)3
A3-D3

=0,

and a division of the numerator and denomenator by D3 would still further exhibit the ultimate identity of DR. RUTHERFORD'S Solution and my own. Since the discussion of LAGRANGE, this is no more than we might have anticipated, à priori, and it in no degree detracts from the originality or value of DR. RUTHERFORD'S solution.

DR. RUTHERFORD'S y and z are the two values of my z with the signs changed. The functions

a-3b, ab-9c, and 6-Зас play a most conspicuous part in the theory of cubics. [See Equations (7), (8),

&c, of DR. RUTHERFORD'S "Complete Solution," &c., and elsewhere.]

JAMES COCKLE.

2, Pump-Court, Temple, September 23, 1851.

A BAROMETER WITH AN ENLARGED
SCALE.

Sir,-In this barometer a light fluid is introduced upon the top of the mercurial column of the common barometer, the tube of the instrument being enlarged at the point of junction of the two fluids, by which device an instrument of equal, or superior, extent of scale may be ob

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A is a cylinder of vulcanized India rubber, with a rigid top fastened to the pump-rod P, which is to be worked by a

common lever-handle; E leads to the well, and F to the air vessel, or reservoir.

The valves C and D are like those of the ordinary forcing pump. On raising P, the partial vacuum produced inside of A will cause the cylinder partly to collapse, as at M, and this is the only reason why it should be made of thick vulcanized India rubber. The resiliency of the cylinder will greatly assist the down stroke of the rod P. And there being no piston or plunger, the only wear and tear will be in the valves.

This plan, it may be said, resembles that of Shalders' Pump, but the difference

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BOARD

OF HEALTH REPORT ON THE WATER SUPPLY OF TOWNS. (Continued from p. 374.)

Much as water power has been employed in giving motion to machinery, it is believed that the raising artificially a large body of water at one spot, to be distributed from thence in portions as an occasional hydraulic power, was first proposed by Sir Samuel Bentham in the year 1812, in his official indicator of the Desiderata in a Naval Arsenal. Article 15 of that communication stated, amongst other items to be provided by waterworks, the "giving or transmitting motion in some cases to machinery along the range of the pipes." Although his plan for a naval arsenal at Sheerness was not adopted, it was known, to the private engineer subsequently employed there, yet neither water nor fire-extinguishing works were provided by him-but afterwards the official engineer (Mr. Mitchell)* proposed and carried into execution there both water and fire-extinguishing works, and provided plugs upon the mains ready for the application to them of hydraulic apparatus, such as would be suitable for the performance of such laborious operations as are of a temporary nature. He was not fortunate enough to convince a superior officer of the eligibility of this mode of employing hydraulic power; yet, as his provision of pipes and plugs remains in convenient parts of the yard, they would now afford opportunity, at little cost, of ascertaining the practicability and economy of this mode of employing the force of a powerful steam engine for temporary services at different and distant places.

"Mr. Philip Holland has illustrated the convenient application to industrial purposes of the hydraulic power derivable from the constant supply."

"At present many trades employ very small steam engines for purposes that may, almost as cheaply. be accomplished by hand; for instance, coffee-grinding. There are many purposes for which steam might be

* Mr. Mitchell from the year 1803, bad been employed in Sir Samuel's establishment of millwrights in Portsmouth Dockyard, and was selected by him in 1809, to superintend the introduction of water and fire-extinguishing works in Plymouth Dockyard.

substituted for manual power with advantage, were it not for the cost of skilled labour required to attend to it, and the expense and trouble of keeping up the steam when the power is not wanted. If some bydraulic engines (such as the tourbine) were employed and worked by water from the pipes -which could be set to work and stopped in an instant, which consumes no power except when at work, which requires no skilful mechanic to work it, and is quite free from risk from fire or explosion; there is no doubt but that numerous applications of such power would be introduced which are as yet scarcely thought of. It would be easy to work cranes and hoists for raising or lowering goods or persons in warehouses,

where the occasions for their use are not sufficiently numerous to have a steam engine economical. Such an instrument would work presses in the smaller printing-offices, where it is not worth while having a steam engine. For many purposes a simple hydraulic press, with a large cylinder acted upon by the direct pressure from the pipes, would be sufficient for packing. In others, Bramah presses might be worked by the hydraulic engine. Turners might work their lathes, and smiths their bellows, by water-power; chaff might be cut and oats and beans crushed by the same means; in fact, it is impossible to mention all the various uses to which it might be applied if water were supplied constantly and at high pressure."

Mr. Holland was aware that there would be power lost by lifting the water thus, " by the amount of friction lost. But large engines are employed for pumping, and small ones are got rid of." "At a very small cost any person wishing for the services of a one or two horse engine for an hour or two a day, might have it without trouble, risk, or uncertainty; " and it would be much used, " if the charge for the power were not very much more than the cost of raising the additional water required, and the expenses attending its distribution." The Board express their opinion, that "though existing steam engines, excepting those of the smallest class, would not probably be superseded by this water power;" "yet, having regard only to the public health, they submit that it is desirable that such applications of power may be promoted, as will in any degree tend to check the multip'ication, even of small steam-engine furnaces and the aggravation of the smoke nuisance."

The question-In what manner are pri. vate employers of hydraulic power to be rated for its use? does not seem to have been adverted to. When Sir Samuel proposed a similar application of it at Sheerness,

it was on the consideration, that a Royal Dockyard is, as it were, an individual manufacturing concern, carried on for the benefit of one and the same firm, so that increase of expenditure in one branch, to save a still greater sum in another, is a source of profit to that firm upon the whole-not so the multifarious concerns of the metropolis, for in it, there are as many persons implicated as there are households; it hardly seems just, that private householders should, by an equal water-rate upon houses contribute towards furnishing manufacturers with a cheap primum mobile. It is true, that Mr. Holland contemplates a charge for the power so employed; but water under pressure being laid on to every house, by what inquisition could the occasional use of it as a power be detected? The Report recommends a man or boy amount of it, to be employed for ventilating private houses. Amongst Sir Samuel Bentham's old papers is the project of a "domestic steam engine" for washing, mangling, knife, and shoe, and saucepancleaning, &c., &c.; doubtless, many examples would soon be afforded of the application of hydraulic power to a variety of domestic operations, mostly in the houses of the wealthy and of persons in easy circumstances, whilst the poor would rarely possess apparatus enabling them to profit by such innovations, and it were hard to make the lower classes pay extra for their water, in order to accommodate others with bydraulic power. Discrepancies of this nature, if not foreseen and provided for at the outset of plans, are liable to bring into discredit the most beneficial ones.

Water-meters would ascertain the quantity of water actually consumed; possibly accurate and cheap ones may be devised when a need arises for them, such as would not be too costly for application to every house.

The Board lay considerable stress on the importance of combining with the waterworks of the metropolis, arrangements for the extinguishment of fire, and indicate many towns where such works have been successfully introduced, but make no mention of those in the Royal Dockyards, where they were first established half a century ago, where they have proved on all occasions of outbreak of fire efficacious in subduing it promptly, and which have been copied in all works of the same nature that have been subsequently introduced. The Board's evident desire to collect the fullest information on every point under their discussion renders their ignorance of Sir Samuel Bentham's invention of fire-extinguishing works remarkable; as those works in the several dockyards are of public notoriety, have formed

the subject of many of his official communications commencing in the year 1797, and descriptions of his apparatus were published in the year 1827, in his "Naval Papers, No. 8," and subsequently, both in the Mechanics' Magazine and in The Builder. The Board had been, till last July, equally ignorant of his proposal in the year 1830, (submitted then to Sir Robert Peel; and also in the year 1844, to Lord Lincoln), suggesting the adaptation of the waterworks of the metropolis to the extinguishment of fire, in the same manner as the waterworks at Portsmouth were arranged by him for the double purpose of supplying water, and of extinguishing conflagration. That proposal has appeared at length in Number 1464 of the Mechanics' Magazine; its readers will perceive by the following quotations from the Report, that the Board and its witnesses employ the same arguments that Sir Samuel used in favour of similar works for the metropolis-namely, the importance of immediate application of water at the first outbreak of fire; the delay occasioned by waiting for turncocks and engines; the expediency of keeping hose and apparatus within short distances, and in such custody as to be immediately applicable; the giving to the police means of putting that apparatus to immediate use; the making collateral use of that apparatus with a view to keeping it in good working order, &c, &c.

The Report furnishes much information which shows the accuracy of Sir Samuel's views, and the efficacy of fire-extinguishing works like those at Portsmouth. Mr. W. Baddeley, "an engineer who acts as an inspector to the Society for the Protection of Life from Fire," stated that, "the number of fires last year was 838, and if there had been means of applying water immediately, two-thirds of them would have been stopped immediately."

"Would you say that the means of epplying water in adequate quantity within five minutes of the commencement of a fire would prevent the progress of two-thirds of them?-Yes; about that time "

"In some places has not delay occurred from the turncocks being at wide intervals? -Yes; on the south side of the Thames particularly. It is generally objected by the Companies that none but their own servants shall have command of the fire-plugs, in order to prevent confusion, as, though it is necessary to have one or two plugs open, it is necessary to close two or three others to get the supply."

"Under a nigh-pressure system, of course there would be a much stronger jet given than can be procured by an engine?-Yes, certainly?"

"Then from your experience you have no doubt that the prompt application of water would be most beneficial?-I have no doubt whatever."

The Board after investigating the time that usually elapses before an engine can arrive after an alarm of fire is given, say that "the men must be assembled and conveyed to the spot, the turncock sought, and the plug opened, all operations then performed in the best possible manner, occupying time," which time, "under the most favourable circumstances" will be 28 minutes, when the distance of a fire is a mile from the station, or for half a mile distance, not less than 20 minutes," "during which time the fire is rapidly extending."

The fire-extinguishing works at Hamburgh appear to be precisely similar to those in Portsmouth-yard. Mr. Lindley (the engineer who laid down these works at Hamburgh), was asked, "How soon can a jet be applied? In two minutes."

"Have there been fires in buildings in Hamburgh in the portion of the town rebuilt?-Yes; repeatedly. They have all, however, been put out at once."

There appears to be an excellent arrangement in Liverpool for the speedy conveyance of hose, devised by Mr. Newlands. "It is this-at each fire-station reels of hose, each mounted on a light hand-cart or barrow, are kept; the bottom of the barrow forms convenient lockers for containing the standpipes, nozles, and tools, and the whole apparatus is so light, that a man can run with it. On notice of a fire being received at the station a couple of men set out immediately with one of these reels. On arriving at the fire the stand-pipes are put down, and the hose run off the reels in an instant, and it may be a dozen jets are playing, and the flames nearly extinguished before the engines have left the yard." "Water jets, under high pressure, are available over nearly the whole of the town. Serious fires are now seldom heard of, for before the flames can gain head the jets can generally be played upon them; and this is the only time that there is any chance of subduing them."

In the third Appendix to the Report, there is the transverse section of a street as rebuilt at Hamburgh, after the great fire of 1842, showing the distribution of water for use, and for the extinguishment of fire. Drawings, where men are introduced applying apparatus to use, realize to the general reader what otherwise might be difficult of comprehension, so that the draw. ing in question is likely to forward materially the introduction of fire-extinguish. ing works. The section of the street at Hamburgh appers to be in all respects ac

curate; it shows one man in the street throwing water over the roof of a house, by means of a hose affixed to a fire-plug, whilst another man in the attic floor of the same house is throwing water on its roof from the interior. In the Wood-mills at Portsmouth, provision is made in each floor for supplying a hose with water under a head by simply turning a cock; at Hamburgh, the hose for use in the interior has to be led through the ground-floor of the house and up the staircase, -an arrangement which seems unnecessary, since water, under high pressure, is served by, apparently, a large pipe to every floor of the house. At Portsmouth the fire-plugs on the mains are fixed at different distances, varying from about 50 to 200 feet, according to the description of buildings or works sought to be protected from fire; at Hamburgh such plugs are placed throughout the town at the uniform distance of 40 yards (120 feet). These seem the only variations of the Hamburgh works, from those that have so long existed at Portsmouth.

After the destruction by fire of the terminus of the South-Western Railway, Mr. Quick recommended works closely resembling those at Portsmouth. He states-"I recommended them to have a 9-inch main with 3-inch outlets leading to six standpipes, with joining screws for hose-pipes to be attached; and that they should carry a 3-inch pipe of the same description up into each floor, so that a hose might be attached in any room where the fire commenced."

"In how many minutes may the hose be attached? There is only the time of attaching the hose, which need be nothing like a minute. I have, indeed, recommended that a short length of hose with a short nozzle, or braneb, should be kept attached to the cock, so that the cock has only to be turned, which is done in an instant." Thus is recommended precisely the same arrangement that was from the first introduced in the Portsmouth Wood-mills.

The Board say, that "It appears that fire engines require twenty-six men to work each engine of two 7-inch barrels, to produce a jet of about 50 feet high. The arrangement carried out at your recommendation with six jets, is equivalent to keeping six such engines, and the power of 156 men in readiness to act at all times, night and day, at about a minutes' notice, for the extinction of fires ?-It will give a power more than equal to that number of men."

The Board appear to condemn tanks on the roofs of buildings, though they say that "In many instances, a constant supply of water has been sought to be secured by the provision of large tanks. In some cases, where the apparatus connected with these tanks happened to be ready, the efficiency of the proposed system of a constant supply was proved by the extinction of fires, which, if a few minutes' delay had occurred, would have inevitably destroyed the premises;" yet, they add, "but heavy disasters have shown that such expensive preparations yield only a very imperfect security."

This opinion, adverse to tanks, seems grounded solely on the evidence of one sin. gle person, Mr. Samuel Holme, a builder of Liverpool. Of their failure in case of fire, he gives the following instance:

"Some years ago, the owner of a cottonkiln, which had been repeatedly burnt, took it into his head to erect a large tank in the roof. His idea was, that when a fire occurred, they should have water at hand; and when the fire ascended, it would burn the wooden tank, and the whole of the contents being discharged on the fire like a cataract, it would at once extinguish it. Well, the kiln again took fire; the smoke was so suffocating that nobody could get at the internal pipe, and the whole building was again destroyed. But, what became of the tank? It could not burn, because it was filled with water; consequently, it boiled most admirably. No hole was singed in its side or bottom. It looked very picturesque, but it was utterly useless." A solitary instance of failure, but is it an example of sufficient importance, or described in sufficient detail of perhaps influencing circumstances, to justify the rejection altogether of elevated tanks?

In many cases, as at Portsmouth, an elevated tank, connected with water-mains, would afford an instantaneous supply of water within the building itself. Experience has ascertained that, in the greater number of fires, it has been practicable to enter a building in flames, and to apply a hose in such manner as to extinguish them, even after conflagration had become extensive; but, supposing it to be impossible to enter a structure, the flow of water from pipes within it might be rendered self-acting in case of fire by forming of fusible metal some part of the apparatus. Had part of the bottom of the tank Mr. Holme so ridicules been formed of an alloy fusible at 212°, water would really have been discharged in torrents upon the fire as soon as it had raised the heat to that of boiling water. So, by forming within a building either part of the pipes themselves of fusible metal, or plugs of it in suitable places, water would be introduced as soon as the heat should rise to 212°; farther, by connecting a pipe with a spreader with the pipe, just below

the fusible part of it, water would, self-actingly, be thrown over the whole interior of a chamber.

The preservation of life in case of fire has not failed to engage the attention of the Board; but the Report states that, "Arrangements for fire escapes or other efficient machinery are, if complete, excessively expensive, or, if inexpensive, generally inefficient. To make these arrangements thoroughly efficient as respects the time of application, one complete set of fire apparatus should be provided for every large street, or for each small sub-district." Mr. Braidwood said that "one, with a man to attend it, should be within a quarter of a mile of each house, as assistance, to be of any use, must generally be rendered within five minutes after the alarm is given." At present, scaling-ladders are kept at all the engine-stations, and canvas sheets also at some of them: several lives have been saved by them; but the distance of the stations from each other renders them applicable only in a limited number of instances." Thus, so far, the recommendations of Sir Samuel Bentham have been adopted; but other apparatus, indicated by him as being in use in foreign countries, does not seem to be yet introduced in London. His attention had been particularly drawn, when last he was at St. Petersburgh, to a fire-brigade there, the men of which had charge, each of them, when called to a fire, of either a light ladder, or a hook, or some other of the various contrivances in use in that city for saving life or property.

The Board recommend cleansing the streets of the metropolis by means of jets of water. They observe, that, - "those whose duties have led them to visit courts and alleys in the more depressed districts, after they have been swept by the scavengers' broom, are aware that, though this may remove the larger collections of filth from the pavements, it frequently spreads the ordure over the surface. Such surfaces, with the walls and basements of buildings, can only be thoroughly cleansed by washing."

The trial of a jet d'eau, with a hose affixed to the water-mains, was recommended to the Metropolitan Commissioners of Sewers, and a number of careful trials were made by Mr. Levick, "It appeared that, taking the extra quantity of water required at the actual expense of pumping, the paved surfaces might be washed clean at one-half the price of the scavenger manual labour in sweeping."

The effect of this mode of cleansing in close courts and streets was found to be peculiarly grateful in hot weather. "The

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