for railway purposes; but fortunately for the original patentee, neither in the title of his patent, nor yet in his specification, does he restrict himself, but expressly claims this admirable mode of superseding the use of the air-pump, for purposes enumerated, or for "other places from which it is desired to withdraw air." On the other hand, Messrs. Nasmyth and May claim for the express object of applying this system to atmospheric railways, a claim to which Mr. Carson has a clearly prior title.

While on this subject, it may be interesting to notice that the storing of a vacuum, but obtained by an air-pump, in three, or more cylindrical vessels or boilers, forms a part of the patent claims of Mr. Henry Bessemer, engineer, in his patent for improvements in the manufacture of certain glass, which was sealed 23rd September, 1841, and published in the Mechanics' Magazine for 30th July, 1842.

In thus plainly stating facts, I am far from being actuated by motives of hostility or favouritism, my only desire being to assert the rights of inventors, particularly in a case like the present, when claimants appear who not only are not the original inventors, but who are taking much pains to fix priority in a matter which I have thus shown to be totally unworthy the contest.

Mr. Carson's patent is published in The Repertory of Patent Inventions, N. S., vol. xv., 1841, and therefore it is somewhat remarkable that both Mr. Mallett and Mr. Nasmyth should act, the one by his writings, the other by his procuring a patent for this previously patented invention, as though entirely unacquainted with a patent so recent, and one, which in regard to the important object it proposes to attain, amazingly simple

and efficacious.

"On the means of rendering large supplies of water available in cases of fire, &c.," (vol. 42, p. 137,) containing as it did, some novel doctrines on matters of considerable moment, led to my penning the "Strictures," which appeared in the subsequent numbers of your Magazine (Nos. 1130, 1131, 1133.) These strictures have been met by an anonymous writer, who, under the assumed signature of "A Fireman," affects to get rid of my objections in a very summary manner, without bringing to the task much either of good sense or good feeling.

con

Had the writer of the "Notes fined himself to the temperate discussion of the plain matters of fact and of science controverted by my "Strictures," I should have felt much pleasure in arguing the disputed points. Not content with this, however, "A Fireman" indulges in the grossest personalities, imputes motives, and adopts a vituperative style of argument that clearly shows the animus by which he is actuated.

Such conduct, and such language, from an anonymous correspondent towards a well-known writer, and one of your oldest contributors, has procured for me the most gratifying assurances of esteem from many of your constant readers.

Passing by, therefore, as I can well afford to do, the Augean filth of personalities, I shall address myself at once to the vindication of the opinions I have hazarded respecting certain scientific facts, as opposed to the opinions of Mr. Braidwood; the present paper will be devoted to a subject of considerable importance, and one upon which it is highly desirable correct notions should prevail, viz., the friction of water in passing through leathern hose.

Mr. Braidwood has stated that the loss by friction amounts to five per cent. for every 40ft. length of hose that is employed, (not 24 per cent. as misrepresented by "A Fireman.") Mr. Braidwood's words are, "the loss by friction in the leathern hose reduces the delivery, and of course the height or force of the jet, 2 per cent. for every 40 lineal feet of hose through which the water passes, (vol. xlii. p. 137,) and "the friction increases the labour 21 per cent. for every additional 40ft. of hose." (Ibid. p. 139.) To this proposition I have objected, that the experiments upon which the foregoing hypothesis was based were not to be relied upon, being neither sufficiently

"

numerous, nor conducted with sufficient care, to afford data whereupon to found any practical conclusions. I showed, also, that the experiments, as recorded, were so contradictory and inconsistent in themselves, that it was impossible to attach any value to their results; and expressed my belief, that no sufficient data as yet existed for determining, with any degree of certainty, the real amount of loss by friction in forcing water through leathern hose. I denied that the friction was at any time (as assumed by Mr. Braidwood) a constant or uniform quantity, and enumerated a few of the numerous causes which inevitably occasion variable results.

Without attempting either to reconcile or explain away the inconsistencies of which I complained in Mr. Braidwood's table of experiments, "A Fireman" merely affirms them to be entitled to the greatest reliance, and to show upon what

367

grounds he thinks they are so, he furnishes an authentic copy of some more recent experiments corroborative (as he supposes) of the former ones. Had these tables been furnished, or the experiments conducted by myself, they might have been regarded with suspicion, confirming as they do, in a very remarkable manner, the opinions I have advanced upon the subject. Coming from the other side, however, they may be regarded as entitled to reliance. It is much to be regretted, that with Mr. Braidwood's appliances and means to boot, the experiments should have been limited to only 10 lengths of hose; however, referring your readers to the details of the experiments as given at page 56 of the present vol., I will just place the terminal results of the three sets of experiments in a tabular form, to show your readers at a glance their bearing upon the question at issue :

The details of these experiments prove (if they prove anything) that the friction is in no case uniform. That the friction does not increase either 5 or 2 per cent. for every 40 lineal feet of leathern hose. And that the friction decreases as the pressure and velocity increases. The ratio of increase in the friction under diminished pressure is very remarkable, and would lead us strongly to suspect the presence of some disturbing element which had escaped the experimenter's ken.

It will be seen, that in one case an increase of 65 feet in the pressure diminishes the friction but 0.1 per cent., while, in another experiment, an increase of only 17 feet in the pressure actually diminishes the friction 0.7 per cent.! Will "A Fireman throw any light upon these singular phenomena, or explain away the inconsistencies I have pointed out? At any rate, your readers will require something more than the assurances of an anonymous writer, that

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Mr. Braidwood's theory of a uniform friction of 5 per cent. per length, so far from being demonstrated, is completely negatived by his own experiments. "A Fireman" says, (p. 55,) "the hose may of such a length, and the friction consequently so great, that there would be a total loss or absorption of the forcing power employed.” Now, I beg to say there is nothing "startling" to me in this proposition; on the contrary, I hold it to be indisputably true. The only question is, what length of leathern hose will it require to accomplish this absorption ? According to Mr. Braidwood's

theory of a uniform loss of 5 per cent. per length, 20 lengths of hose would absorb the working power; or, if 21 per cent., 40 lengths would do it. But the whole of Mr. Braidwood's last experiments go to show a continually decreasing ratio of friction for every length that is added, so that, if hose enough be employed the friction will at last benothing!

Now, I beg to state positively, as the result of actual experiment with a brigade size engine, (7 inch barrels,) that 40 lengths of hose will not absorb the whole of the forcing power; on the contrary, with 40 lengths of hose attached, and only a small number of hands on the engine, a very considerable forcing power has been available for throwing a jet of water. "A Fireman" objects to my pressing the principles of Mr. Braidwood's theory to their natural and inevitable conclusion, but I hold this to be a legitimate and logical mode of exposing their absurdity.

If two engines, exactly alike in every particular, and equipped with the same size hose and nose-pipes, but the one having one length of hose affixed, and the other twenty, are worked at the same speed, and consequently deliver the same quantity of water, the two jets will not rise to the same height, although the initial velocity of the water is the same in both cases. In the one case there would be a greater absorption of power, because, with the twenty lengths of hose, the men would have to exert more force to maintain the same speed as the others, and we should have a diminution in the height of the jet, but no reduction in the delivery! Will "A Fireman please to explain this circumstance, or reconcile it with any of the experiments on which he places so much reliance?

The "loss by friction" of water passing through leathern hose has, from Mr. Braidwood's exposition, become a sort of bugbear that has in some recent instances, to which I need not more particularly allude, been productive of considerable mischief. There can hardly be two opinions about the propriety of working engines upon a fire through as short a length of hose as is consistent with a perfect command of the fire, and the safety of those who work the engine;

but neither of these important matters need be compromised, nor parties deterred from carrying or using long lengths of hose, from fear of all the forcing power being "absorbed by friction."

I remain, Sir, yours respectfully,
WM. BADDELEY.

29, Alfred-street, Islington,
Nov. 11th, 1845.

THE LIVERPOOL FIRE POLICE AND LON DON FIRE BRIGADE.

Sir,-When in Liverpool, a few weeks since, I paid a visit to the head station of the fire police in that town, and much gratification it afforded me, through the kindness and attention of the superintendent, Mr. Hewitt. I assure you, sir, that the good men of Liverpool beat their London brethren hollow, not only in the power, but in the management of their magnificent engines; and I can therefore set my seal to the truth of what Mr. Baddeley says in their favour. Depend upon it the 7 inch squirts of our London fire brigade, whose inefficiency at such disastrous fires as those at Fenning's wharf in 1836, and Topping's wharf in 1843, one would think ought to have been sufficient to seal their doom, will never be abolished until the protection of the lives and property of the inhabitants of this metropolis is taken from the insurance companies, and consigned to the care of the municipal authorities alone. I noticed that each of the Liverpool engines is provided with a long reel, on the top, around which is wound a great quantity of hose, with the branch screwed on the end, and ready for immediate use. The importance of this ingenious plan is readily estimated by those who have witnessed the time lost by the London firemen on their arrival at a fire, by having first to undo several lengths of hose strapped together, and then, unite them until the requisite length is obtained. That anxious exciting work, preparing an engine for immediate use, should rightly occupy but a few moments, yet, although this plan has been long adopted in Liverpool and elsewhere, our sapient London firemen cannot or will not admit its utility. None of the engines belonging to the Liverpool fire police have less than 10 inch barrels, and are capable of throwing jets to the height

so as to double her resistance, and double the cost of running her by doubling the quantity of fuel consumed in a given time, more than doubles her capacity to carry freight, fuel, &c., which explains why large vessels of any kind are found most profitable where there is employment enough for them, and why large steamers can keep the sea longer, and accomplish longer voyages with the fuel they are capable of carrying, than smaller steamers.

Let there be taken, for example, two vessels, one 30 feet wide, 150 feet long, and drawing 10 feet water; and another 40 feet wide, 200 long, and also drawing 10 feet. The displacement (or capacity to carry) of one is represented by 45,000, the product of the three measurements; and the displacement of the other by 96,000. The relative resistances are represented by 300 and 400 —that is, the capacity of the larger vessel is more than 100 per cent. greater than the smaller, and her resistance, and consequently her power and expense, are greater by only 33 per cent.

5. The difficulty of ensuring to singledecked vessels of very great length, such as the President and the British Queen, strength enough, even with deep sides, to prevent their breaking and foundering, constitutes an objection to the excessive increase of size, and prescribes a limit to the practical application of the principle explained in the preceding article.

6. In proportioning engines to vessels intended for steaming only, it is customary to allow a horse power for every two or four tons-giving the highest proportion of power to smallest vessels for reasons explained in Art. 4.-There is a growing partiality for high proportional power, especially for vessels engaged in the transportation of passengers. And for steamers of war it is argued with plausibility, that in their power to obtain great speed, lies an essential portion of efficiency.

7. But experience as well as figures has abundantly proved, that no private capital nor public treasury can bear the expensive drain produced by constant steaming, in any number of vessels performing ordinary mercantile voyages on the ocean, or employed as cruising men-of-war. Neither is it ordinarily possible to sustain the expense, in cases where steam is the principal power, and sails the auxiliary. Experience has, however, further shown, that in many, if not in nearly all cases, mercantile navigation can be rendered more certain and profitable, and the service of men-of-war more certain and efficient, by retaining the sails as the principal power, and introducing steam as an auxiliary; modifying the forms of

vessels somewhat, so as to preserve the adaptation to sails, and yet yield something to the new auxiliary power introduced.

8. The forms of vessels intended entirely for steaming are wholly different from those intended for lofty sails. The forward lines of the steamer are made sharp; for if they were full, the propelling power being applied near the water, by division of forces, the water striking obliquely under the bow, would lift the bow and settle the stern. On the other hand, if those lines in a sail vessel were made sharp, the propelling power being applied at a lofty point on the masts, would serve to pry the bow under, or bury the bow. But this burying tendency is counteracted by the full forward lines of sailing vessels.

Vessels intended for both sails and steam are in these respects a compromise; but it is evident that the full lines which will fit them for sailing, renders them incapable of great speed under steam alone, unless loaded with an enormous weight of boilers, engine, and fuel, which would leave neither space nor capacity to carry anything else. Therefore, we conclude that power calculated to give great speed can rarely be applied wisely or profitably to vessels intended also to possess essential sailing qualities and capabilities, except in the case of vessels of war, which might with advantage have great power in reserve, to be used only in emergencies.

Side Wheels.

9. For vessels which are constructed and intended to be propelled by steam alone and in smooth water, no other plan affords the same advantages as side wheels. These wheels are usually on the extremities of a single shaft extending across the vessel from side to side. For convenience of room in river or passage boats, however, or for the sake of having a second engine to rely upon in case of accident to either in sea steamers, the power is frequently divided in two engines. In such cases, sometimes instead of both wheels being on one shaft, and both engines connected to that shaft, each wheel has its independent shaft, and each engine drives a single wheel only. The advantage of this latter plan for river boats and harbour steamers, is that they are turned quicker and in a shorter space, because one wheel may turn forward and the other back.

In sea steamers, the wheels must be on a single shaft, and both engines connected to that shaft; for if by the ship's heeling one wheel is thrown out of water, it offers no resistance to the rapid and dangerous motion of the piston; but the other wheel, by being