434 BRAITHWAITE'S STEAM FIRE-ENGINE. BRAITHWAITE'S STEAM FIRE-ENGINE. SHORTLY after the conflagration broke out, to which the Argyle-rooms fell a prey on Friday last, a new fireengine, worked by steam, on the same principle as "The Novelty" steamcarriage, and manufactured by the same ingenious and enterprising engineer, made its appearance on the scene, under the direction of Mr. Alfred Braithwaite, and earned for itself universal admiration, by the powerful services which it rendered on the occasion. It was worked incessantly for nearly five hours: discharged upon the burning pile and adjacent buildings from thirty to forty tons of water per hour and sent its jet of water completely over the dome of the building, a height of at least eighty feet. We have seen it stated in some of the newspapers that none of the engines was able to reach the dome; but this statement can only be correct as regards the old engines. Several gentlemen, who were present at the fire, have assured us, that they saw distinctly the water ejected from Mr. Braithwaite's engine quite over the dome; and one of the same individuals previously witnessed a private trial of the engine, when it threw water over a pole ninety feet high, erected for the purpose of the experiment. The expenditure of fuel to produce these wonderful effects was only about three bushels, during the whole five hours; and the help of two men only sufficed to keep the steam up, and superintend the working of the engine. The strong interest which the performances of this new fire-engine have excited, has induced us to lose no time in making ourselves acquainted with the details of its construction; and it is with much pleasure we are thus early enabled to present our readers with the very correct engraving on the preceding page, and the following descriptive particulars. In all that regards the generation and application of the steam, the same contrivances are adopted in this engine as in "The Novelty;" but there is a difference in the form of some of the parts, and in the general arrangement. The furnace and boiler, K, are exactly the same as those of "The Novelty," but of less power. The hot air-pipe, instead of being vertical, has received a serpentine form, (B) which adds much to the appearance of the engine in point of elegance and compactness. This pipe has also been made to turn on a swivel, so that the engineer or driver of the carriage can turn the mouth of it in any direction which he finds most convenient. The blowing-apparatus is here placed in front under the driving-box, and is worked by the tappet-lever C. The cylinders, M, are placed horizontally; and each steam-piston is connected with the water-pump (E), plunged by one rod working through the two stuffingboxes, so as to form its own parallel motion. A cross-head, attached to the piston-rod, sliding on the frame which supports the two cylinders, works the tappet-lever C, connecting with the slide D, the feed-pump F, and the blowing-apparatus. blowing-apparatus. The feed-pump and blowing-apparatus have also separate appendages for working them by hand occasionally; and provision has been farther made for regulating the stroke of the former according to the work of the engine. P is the mercurial-guage, R the safety-valve, S the feed-box to the furnace, and T the eduction or waste steam-pipe. A box, O (owing to want of room only partially represented in our engraving), serves to hold the coke or other fuel, and as a platform for the assistant engineer. The steam-cylinders are 7 inches in diameter; the length of the stroke of the pistons 16 inches; the number of strokes per minute from 35 to 45; the power barely 6-horse. We come now to the parts of this apparatus peculiar to it as a fire-engine. The globe or sphere A, is the air-vessel; the water-pump E is 6 inches in diameter; the oblique pipe GG, is one of the suction-pipes. The action of the water-pump being double these suction-pipes, either connect with the tank H, or in the common way at J. The object of having the tank H, is to enable other engines to supply this one with water in situations such as narrow streets and alleys where a supply of water, close at hand, cannot be obtained. MR. LUBBOCK'S supplementaRY DISQUISITION ON THE TIDES. 435 But it must not be supposed from this, that there is any necessity for placing this engine in a particular situation, in order to connect it directly with the water-mains. Its suction-pipe is a common perforated rose, and it may lie in any part of the water-way with the suctions of other fire-engines, and take its supply from the same source. It worked with one jet only at the late fire; but is constructed to operate with one or two jets, as occasion may require. The total weight of the machine, with its complement of fuel and water, is incredibly small; not more than 45 cwt. Although the engine we have now described is the first of the kind which has been brought into public operation, it has, we understand, an elder brother, of still greater capabilities. The other engine we allude to is stated to be of 10-horse power, and capable of throwing ninety tons of water per hour, either by one large jet or by four smaller ones. A private trial of it was made lately in the presence of a number of gentlemen connected with the Fire-offices; when the only exception taken to it was expressed in the shape of an apprehension that it would be found, in reality, too ful. We presume that what was meant to be said was, that a ton and a half of water ejected per minute in a single jet might as readily knock down some houses as preserve them from the flames; and there is no doubt such would often be the case. power But as this body of water can be as conveniently discharged in four different jets as in one, there can be no serious reason to apprehend any actual inconvenience on this score. MR. LUBBOCK'S SUPPLEMENTARY DIS- Another paper from the pen of that ingenious and profound investigator, Wm. Lubbock, Esq., F. R. S. Almanaccomputer for the Society for the Diffusion of Useful Knowledge, &c. &c. on the subject of the tides, appears in the last Number of the " Philosophical Magazine." The manifest purpose of this paper is to vindicate himself as well as he can from the charges of ignorance and blundering which we had brought against him (for by nobody else have his computations been found fault with): yet with a candour which throws even his modesty into the shade, he carefully refrains from any literal reference to the journal which has extorted from him this supplementary vindication! By thus omitting to name his assailantsto specify to what particular bill of accusation his vindication has referencehe has reserved to himself the power (a power which he has very freely exercised) of noticing such points only of the case against him as it suits him best to notice; the power also of sheltering himself afterwards under any form of excuse for his silence in regard to other charges as that he was not aware of their existence, or had overlooked them, or thought them beneath notice, or any thing else equally satisfactory and true. People may say, perhaps, that Mr. Lubbock has been thus enabled to shape his defence more according to his own convenience than to the facts of the case; that a person who felt justly confident in his strength, would have met his antagonists manfully, face to face and foot to foot; and that no one who had devoted himself with high-mindedness and sincerity to the diffusion of useful knowledge, would have sought to draw a veil even over the slightest of his own errors. But what will not people say? We live in a world full of narrow notions, and volunteer public instructors are not to be judged of by vulgar rules. Mr. Lubbock commences his defence with again adverting, for the purpose of indirect censure, to "the studious secrecy" of the computers of tide-tables published in this country. Now, we should be glad to know why the calculator of a tide-table, any more than the manufacturer of a water-proof hat, or water-proof boot, should reveal to those who will, in consequence, oppose him in his calling, the secret of his art? If the banking-house of Lubbock and Co. have any mode of getting money peculiar to themselves, is there any want of liberality or of honour in their not sending a circular to every banking-house in the metropolis to show how the gain is effected? But is there really so much secrecy?" Are there not many wellknown rules and tables for computing high-water, as those of Heath, Robertson, Mackay, Garnett, Brisbane, Mendoza Rios, the "Imperial Almanac," &c.? Some of these rules are very excellent and scientific: four, at least, of them involve the principle of Mr. Lubbock's table, given at p. 5, "British Almanac ;" and even the worst of them, 436 MR. LUBBOCK'S SUPPLEMENTARY DISQUISITION ON TRE TIDES, as we shall soon see, will give the time of high-water (the effects of winds and land-floods excepted) within a quarter of an hour, when what is denominated "the establishment of the port" is correctly assumed. For aught Mr. Lubbock knows to the contrary, some of these rules may be employed by other computers; and whether the fact be so or not, his querulous tones are much out of place. We have long thought that the transcendent mathematics of the present day often leads its votaries astray from practical common sense, and Mr. Lubbock's mode of writing is an illustration. His sentences are usually so unconnected, that it is difficult to reduce to order any remarks upon his performances. We will endeavour, however, to notice what is most important. He says, 6. as long as the bed of the river continues the same the tide will be regularly transmitted to any point of it, modified only by an alteration of the constant quantities in the formula which the theory gives. This will be the case, even if we suppose the tide which we have here to be compounded of two tides, which arrive by different courses, and after different intervals, as might very easily be shown to follow from the nature of the expression, by which the height of the water at a given place is represented." Since this is so " easily to be shown," we regret that Mr. Lub. bock did not attempt it, with an especial reference to our objections at p. 295, No. 332. His quotation from Laplace bears scarcely more upon the point, than a quotation from Hoyle's "Laws of Whist." Mr. Lubbock is, however, so firmly persuaded that the sequence of the tides should be " as regular" in the port of London as in the ocean, that he is positively blind even to the evidence on the subject which his own paper presents. He gives a table of the times of high-water, morning and afternoon, for the first 13 days of the present year, as observed at the London Docks and at St. Katharine's Docks (the latter being about half a mile nearer London Bridge than the former), from which it appears that no less than seven times in the 13 days, the high-water was earlier at the docks most remote from the Nore than at those lower down, while on the other six days the highwater occurred first at the lower docks! Yet this strange circumstance, far from startling Mr. Lubbock, seems to be regarded as a proof of a regular transmission! But, in truth, nothing seems to move this gentleman from his imper turbable serenity. He mistook (or his informer did) Rotherhithe for Wapping church; but this point, though he "regrets it," can, he assures us, "be of no consequence whatever!" He disregarded the declinations of the sun and moon, and he neglected the equation of time; he neglected half the observations, and so on: but (p. 126, No. 38, "Phil. Mag.") all these things, he farther tells us, "CAN have no perceptible influence !" No: nor can any other blunders, or any other neglects, render Mr. Lubbock's results less worthy of confidence than they now are. 66 But it appears, that our objections to applying Laplace's theory to places separated from the main ocean by long and narrow channels, as is the case in the port of London," are nugatory, because the times of high-water occur as regularly in the Thames as in the sea. Indeed! then what becomes of the effect of the wind in different reaches of the river? What of the effect of freshes and land-floods? And how happens it, that in many parts of the river, the tide continues to flow upward for twenty minutes, or half an hour, and sometimes more, after the surface of the water has begun to descend? Some of our papers in subsequent Numbers, in reference to the effects of the old bridge, may farther exemplify this. Meanwhile, we may adduce two or three proofs of the want of that regularity which Mr. Lubbock believes to exist, notwithstanding the evidence to the contrary adduced by himself. Deptford Dock-yard is, we believe, from 3 to 4 miles lower down the river than the main entrance to the London Docks. Now, we have had an opportunity of comparing the times of highwater at those two places, from authorised records, twice every day, for the months of July and November last; and though, as might naturally be expected, the high-water occurs usually earlier, by from 10 to 20 minutes, at Deptford Dock-yard than at the London Docks, yet, on July 4th, 6th, 8th, 11th, 12th. 16th, 17th, 18th, 22nd, and 23rd, and November 6th, 18th, 20th, 27th, and 28th, the times of high-water are recorded as precisely the same at both places; while on July 20th and 21st, and November 2nd, 21st, 22nd, 25th, and 29th, the high-water occurred earlier by some minutes at the London Docks than at Deptford: on three of these occasions the difference was more than half an hour! These discrepancies are doubtless in some measure owing to carelessness in the records, and that at MR. LUBBOCK'S SUPPLEMENTARY DISQUISITION ON THE TIDES. 437 the London Docks, especially, shows some great irregularities; but others are manifestly to be imputed to the effects of winds and land-floods, and are totally ruinous to Mr. Lubbock's theory of regular transmission. But what will not a mere theorist do to resist the impression of facts when they run counter to his notions of differentials and Laplace? Mr. Lubbock, referring to his mean result from observations (9.52452) of which we spoke at p. 312, No. 333, says, this mean result is not affected by the neglect of the equation of time." Of course not, according to Mr. Lubbock's notion of things; nor would it if the equation of time had sometimes been 16 hours instead of 16 minutes. But a crude notion is one thing, and a clear principle is another; and they do not often co-exist in the same mind. Without dwelling, however, upon the neglect of the equation of time, are there not other circumstances which may affect the mean result, besides those specified in our former articles? Is it quite clear that the time of high-water is always the same (or that it always varies by a regular difference) in the mid-stream of the river and at the gate of the main entrance of the London Docks? Will they be the same whether the gate be sometimes shut and sometimes open, or always open, or if both the main entrance-gate, and the Hermitage-gate, be both constantly open, the tide freely entering one gate and passing out at the other? A cautious investigator would hesitate upon all these points; but to each Mr. Lubbock would most probably reiterate, "this is"-" this can be of no conse. sequence whatever.” is " p. 66," Mr. Lubbock proceeds, if we rightly understand him (p. 137) to admit that "the neglect of the equation of time" perhaps perceptible in the table at In the Companion to the Almanac," p. 61, he remarked, "the effect of the change in the sun's declination is clearly perceptible in the table, pp. 66, 67." Then he seemed confident, now he is in doubt. Both causes have manifestly operated in producing the palpable irregularities of that table; and more than either, most probably, the defective observations and the unscientific mode of deducing the means. In January and July, the sun's declinations, south and north, are nearly the same in magnitude, and the equation of time is of the same kind in both, varying in January from 4' to 13', in July from 3' to 6'. Yet, when the moon culmi nates at noon, we have in January for the quantity preceding, 2h. 5m., in July 1h. 28m.! So again, in May and July, we have against corresponding hours, 2 10, 1 28; 1 49, 1 35; 0 45, 1 15; 0 48, 1 20; 0 40, 1 21 ; &c. Other irregularities the reader may trace at his leisure. The general result is, that from a series of mere arithmetical means of numbers occurring most irregularly, and varying from Oh. 29m. to 2h. 22m.-the means themselves again varying in the twelve months from 1h. 13m. to 2h. 56m.-he infers a value of *λ-λ', that is, in plain English, of the establishment of the port 2 hours! We will venture to say that Mr. Lubbock would have ascertained this fact, in a far more satisfactory manner, by asking any waterman who plies at Hermitage-stairs, what is the usual time of high-water at new or full moon, at the London Docks: but then what would have become of the 9000 observations of the rival clocks at Rotherhithe and Wapping churches, and of that ingenuity which has contrived to exhibit at pp. 66, 67, differences for every hour of the twenty-four, when by the investigator's own acknowledgment, the observations during the day light hours only were regarded. We feel, however, that we may be thought to resist conviction, when we make these strictures in the face of the table in the "Philosophical Magazine," where Mr. Lubbock compares the times of high-water for 13 days in January with the announcements for the same days in the "British Almanac." We have already adverted to one strange irregularity in this table, with reference to the times of high-water at St. Katharine's and the London Docks. Let us now add, that 13 days, with the river clogged with ice, are not sufficient for a fair trial; that Mr. Lubbock's application of the equation of time to columns computed as his were, is questionable; that his mode of taking the mean is often fallacious; and that other tables to which his are opposed, when tried by the same test, give better mean results. Thus, taking White's" Ephemeris" for example, deducting from each time of morning high-water, 30 minutes, the difference between A-λ at the London Docks and at London New Bridge, and adding to the sum of the 13 times, 1h. 24m. for the correction of equation of time, the amount is 69h.33m.; while the amount of the observed times at the Very distinguished mathematicians, like Mr. Lubbock, can make no progress without the aid of Greek letters.-What pedantry! 438 MR. LUBBOCK'S SUPPLEMENTARY DISQUISITION ON THE TIDES. London Docks was 69h. 30m. Mr. L.'s amount is 70h. 10m.: hence, while his mean error is, by his own showing, 4 minutes, the mean error in White is only a quarter of a minute. Proceeding in the same way with Bulpit's table of high-water at the East India Docks, using 20 minutes for the difference of A-A' at the East India and London Docks, and omitting the correction for the equation of time, Mr. Bulpit's table being given for mean time (as we would venture to suggest it would be better to make White's in future) the amount is 70h. 13m. and 70h. 13m.-69h. 30m.—43 ̧ nearly, for the mean error. The indi- Thus far, the comparison shows that White's and Bulpit's tide-tables are both better than Mr. L.'s, according to his own criterion. But we may proceed a step farther, and show, that one of the oldest, and probably one of the least scientific rules for finding the times of high-water, gives a better mean result, than can be extracted by Mr. Lubbock from good observations, collected in 24 years, methodised carefully by Mr. Dessiou; notwithstanding the aggregate advantages of "the kind interference of Captain Woolmore," "the superintendence of Captain Eastfield," the valuable mass of advice supplied by "the Committee of Superintendence,' Euler's thin medium revolving about the sun, "Materia subtilis in gyram acta," &c. differentials, Greek letters and accents, and (let it not be forgotten) the church clocks of Wapping and Rotherhithe. Heath, in his "Royal Astronomer," published 70 years ago, remarked, that at London the high-water at the moon's quadratures did not happen 6 hours, but usually about 5 hours later than at the preceding new and full moon; and from this observation, he presented in one of the annual numbers of his Palladium," this rule:-Five hours divided by the interval in days, from new or full moon to the succeeding quarter, gives the average daily addition to the high-water at the said new or full moon till the quarter. And, seven hours divided by the interval in days from The following remark in Mr. Bulpit's pamphlet may possibly be instructive to Mr. Lubbock, and his friends of the Diffusion Society:"In the Black wall-reach of the Thames, the stream of flood, in strong spring-tides, begins to run up about 4h. 20m. before high-water, and ends about 40m. after high-water, when the side has fallen about one foot at the dock-gates." 13 =3 min. first or last quarter to the succeeding full or new moon, gives the average daily number (in minutes), to be substracted from the time of high-water at full or new moon, back to the preceding quarter. A skilful computer would, of course, change the average numbers thus obtained by slight differences, so that, while the mean result remained the same, they should run in a regular progression; but, without having recourse to this expedient, we have for the times of high-water on the successive days:1st. 6h. 17m.; 2nd. 7h.; 3rd. Sh.; 4th. 9h.; 5th. 10h.; 6th. 11h.; 7th. Oh,; Sth. 1h.; 9th. 2h.; 10th. 2h. 43m.; 11th. 3h. 26m.; 12th. 4h. 9m.; 13th. 4h. 52m. The amount of all these is 69h. 27m.; the amount of the observed times 69h. 30m. Thus, this avowedly grossly approximative rule, supplies an average result nearer by 40 minutes than the result of Mr. Lubbock's recondite speculations, even according to his own test. After writing the preceding remarks, we thought it might be worth while to compare also the observed times of high-water at the London Docks for the first thirteen days of the present year, as exhibited in Mr. Lubbock's last paper, with the observed times at Deptford Dock-yard; and such as the result is, we lay it before our readers (confining ourselves, however, to the morning column merely). On the 3rd, 4th, and 12th January, the time of highwater is recorded to have been precisely the same at both places, though, as before stated, the one place is between 3 and 4 miles lower down the river than the other. On the 5th, 10th, and 13th, it was highwater only five minutes later at the London Docks than at Deptford; on the 6th, 7th, and 9th, fifteen minutes later on the 8th, twenty-five. On the 10th it was high-water at the London Docks at 2h. 35m.; at Deptford at 2h. 40m.; that is to say, soonest by five minutes at the place which the tide reached last. The difference between the time of high-water on one day, as compared with the day following, varied |