PRIZE CHRONOMETERS. posite sides converge or incline towards the top. The dasher consists of two arms, hung on pivots or pins on each perpendicular side of the churn, which,projecting down almost to the bottom, have inserted between them a number of slats, or thin pieces of wood. On the top of these arms are framed two levers at the centre, so as to project horizontally each way, and connected at each end with rounds. The dasher moves or vibrates in a manner similar to that of the patent washing-machine. By this means a powerful force is mechanically applied to the cream, uniformly straining and agitating the whole at every vibration, with great ease to the operator. Children can use it. The principal specific improvement in this machine is the pendent swing-dasher. The advantages mentioned are at once obvious from the description. I am, Sir, Your obedient servant, CLIO. PRIZE CHRONOMETERS. SIR,-Having just received the late Numbers of your useful Publication, to which I am a constant subscriber, I beg leave to intrude a few observations, suggested by what has appeared in Numbers 93 and 95, under the head of "Prize Chronometers." Your Correspondent, under the signature of " A Real Workman," takes for granted, that the Government, in receiving chronometers for trial at Greenwich, had in view the encouragement of real workmen in the branch of chronometry, and not the mere sellers of chronometers. Upon this head I differ with him, and am more inclined to believe, that the object of the Government was to obtain, if possible, good chronometers, without regarding whether they came from real makers or mere sellers. Should, however, your Correspondent be correct in his opinion, nothing certainly could be more foreign to the object in view, than the admission of a very large pro 213 portion of the chronometers that have been sent for trial; as they are known, to most of the practical workmen in the trade, and also to many gentlemen of science, not to` have been made by the persons whose names they bore. But your Correspondent has acted indiscreetly, in asserting of Messrs. Murray and French, that they never made a chronometer themselves. His honest zeal for the interests of" real workmen" should not have led him to this, since he will find it a difficult task to prove this assertion, which he has been challenged by Mr. French to do. However strong may be the conviction in the minds of real workmen, that the majority of those who call themselves manufacturers of chronometers are neither qualified by their scientific attainments, nor by their practical experience, to make a chronometer, it is next to impossible to furnish sufficient and satisfactory evidence that they never did make one. The communication of this Correspondent did not, however, as a whole (as it appears to me), call for the very harsh language used by Mr. French, in the reply which appears in your publication of the 18th instant. The want of temper which pervades that reply, is as much to be lamented on Mr. French's account, as it is on behalf of truth and science; for the cause of the latter is in no chance of being promoted by angry disputation, ither are the private interests of individuals likely to be much benefitted by reviling those who may in any way become their antagonists. In reference to the charge of your Correspondent of the 4th instant, Mr. French says, that "the motive is too obvious to be mistaken, and too malicious to have any effect with a discerning public." Now, it appears to me quite clear, that, obvious as the motive of this writer is, Mr. French has mistaken it, for he infers malice from it—a thing of so base a description, that it ought not to be inferred from the motives of any man upon slight grounds. The evi dent motive of the writer was, to awaken the attention of the publie to the fact, of certain gentlemen having been rewarded for machines which, he believed, they never made; and which rewards, in his judgment, ought only to have been given to those who were really and effectively the makers of the said machines. I shall leave to the good sense of your numerous readers to determine how much this savours of malice, for I do not deem it necessary to waste a moment's time in the inquiry myself. a Mr. French gives an unqualified denial to the charge of never having made a chronometer, and of being but a mere" dealer and chapman;" but, with all due deference to Mr. French, I must say, that a declaration on his part, that he really made the chronometer in question, and also those which have appeared, and those which now are, at the Royal Observatory, bearing his name, would have been far more effective in silencing the com- . plaints of real workmen than any thing which he has said. Indeed, unless Mr. French can affirm that he is the real maker of the machines above mentioned, I must be excused for regarding him but as dealer and chapman," so far, at least, as regards the article of chronometers. I know nothing personally of Mr. French, but am very willing to give him credit for all the skill and ingenuity which you, Sir, say he possesses; and as true genius and real talent have nothing to fear from the jealousy or the animadversion of rivals, whatever may be unjustly said or written in the spirit of rivalry, can only have the effect of placing the merits of Mr. French in a more conspicuous light. I can assure Mr. French, that, although a real workman, I have not the honour to be one of his rivals; I therefore trust, that I shall not lie under the suspicion of being actuated by envy or jealousy, or any other unworthy motive. I am not one of the "real workmen" who have in any way complained that injustice has been done in the distribution of prizes, and in addressing you, are not animated by that esprit de corps which may be presumed to appertain to that class. My only motive in this communication is, to call into action, if possible, the talents of those persons who may be much better qualified than myself to enlighten the public, as to the real merits of the several competitors for the prize chronometers, and to endeavour that, if the rewards go into the pockets of nominal makers (which, it has been asserted, they sometimes do), the empty honours shall at least be decreed to the real ones. In order to avoid every misapprehension as to the meaning of terms, and to prevent the possibility of my being supposed to understand, by the terms "real maker," a person who shall make the machine, in all its parts, from beginning to end, I beg leave to add, that I consider the chronometer-maker to be distinguished from the watch-maker, by his knowledge of all those parts that distinguish chronometers from the best watches, and by his competency to execute them. For example, the escapement, with its functions; the balance, with the means by which the effects of different temperatures on the spiral spring are neutralized; and, lastly, the spiral spring, with its properties of rendering the vibrations of the balance isochronal, or of retarding or accelerating them in any required degree. It may also be added, that the good chronometer-maker should possess scientific knowledge sufficient to see that the other parts of the machine, which are made by less talented workmen, are arranged and executed in the best possible manner; but this latter qualification, it will be agreed, is requisite to constitute even a good watch-maker. I must object to Mr. French's definition* of a chronometer, which, * I hope it is not upon this definition that Mr. French denies the truth of the meter; for it is certain that he could not assertion, that he never made a chronohave served the laborious apprentice ON THE STOPPING OF ASTRONOMICAL CLOCKS. he says, I abstain, Mr. Editor, from of fering any remarks on what you yourself have written on the subject in question in Number 95. No one can deny the justice of your general reasoning; but it must also be admitted, that what you have therein said on the merits of Mr. French, will only apply to him on the supposition that he is the real maker of the machines to which you allude. If he be the real maker of those machines, too great praise cannot be given him, nor too great a reward bestowed on him (for unquestionably they are of great excellence), and Mr. French can only add to his fame by avowing himself such; if he be not the real maker, the honours you have done him appertain by right to some other person or persons, and since, according to your testimony, the whole world gives Mr. French credit for being a man of talent, I trust he will give the whole world an opportunity of allowing that he is also a man of candour, by publishing, through the medium of your valuable Magazine, the names of the real makers of those machines, and thus place the laurels on the brows of those whom they ought to adorn. I am, Sir, Your very obedient servant, 188, Fleet-street, June 30, 1825. ship, which he states he did, without having made many "machines for the admeasurement of time." Vertical and other watches are machines of this description, but they are not chronometers, in the ordinary acceptation of the term, though they would appear to be so according to Mr. French's defi'nition. 215 One cause of the stopping of delicate astronomical clocks, has been supposed to be the attraction exerted by the weight on the bob of the pendulum, when the two become opposite to each other. The very minute quality of this attractive force renders it difficult to conceive that it can so disturb the motion of a heavy pendulum as finally to stop it, and the following observations induce me to believe that, in the cases which have been thus explained, the true cause is very different. I have a French clock, with a very heavy half-second compensation pendulum, fitted with Lepaute's dead-beat escapement. A weight of one and a half pounds, in descending eleven inches, keeps it in motion a week. The pendulum is supported by a strong upright bar of steel, which also supports the pulley, over which passes the cord which suspends the weight. This clock I found frequently to stop when the weight descended nearly opposite to the pendulum, from which it was then distant about three-fourths of an inch. This I attributed to the attraction of the weight and pendulum, and determined to remove the weight to a greater distance. Before this was done, however, on attentively observing the clock, I found that, before it stopped, the weight acquired a considerable oscillation, evidently communicated from the pendulum through the common support. To destroy these oscillations, I placed a perpendicular wire by the side of the weight, the whole line of its descent: on this a ring was permitted to slide, and was connected with the weight by a delicate spring. This spring, by constantly pressing the weight towards one side, prevented the oscillations from taking place, and com 216 OBJECTIONS TO MR. HIGGINSON'S PLAN, ETC. pletely effected the object, and the clock has since continued to go without any interruption. The experiment has been often repeated, of supporting two clocks on the same horizontal beam: if one be set in motion, it will, in a short time, communicate its motion to the other, and if both pendulums be of the same length, they will continue their beats with perfect isochronism. This sympathy, which also exists between two watch balances which are supported by the same plates, has been ingeniously used in practice by Breguet, who has constructed clocks and watches, each including two distinct movements, having no connexion together except by the plates which form the common support. In these time-keepers the pendulums and balances beat perfectly together, and thus one pendulum or balance is made to correct the irregularities of the other. If this experiment be made when the pendulums are of different lengths, the clock first in motion will be stopped. This effect can be transmitted through media apparently very solid, and probably has taken place in the instances when the clock's stopping has been attributed to the attraction of the pendulum and of the weight; in such cases the weight suspended by its cord becomes a pendulum of nearly the same length as that of the clock. The remedy is easy, merely to conduct the cord of the weight to a different support from that which sustains the pendulum. OBJECTIONS TO MR. HIGGINSON'S SIR,-The facility with which new inventions are brought before the notice of the public, through the medium of your highly useful Magazine, cannot fail of producing a great deal of good to the community, particularly as your pages are open to discussion, by which the merits of any plan or inven tion may be fairly investigated, and its utitity or inutility be established. Now, Sir, I am disposed to think that Mr. Higginson's invention, described in your 94th Number, is particularly obnoxious to animadversion. It reminds me of the fable of the mice assembled in council, in order to adopt some plan of security against the ravages of puss, and the young mouse's proposition as to the bell being suspended to her neck. But as Mr. Higginson may, perhaps, be prepared with answers to any objections offered to his plan, I will, with your permission, ask him a few questions, by the answers to which he will have an opportunity of laying the merits of his invention in a fairer point of view; and if he can overcome the obstacles I shall name, he will deserve immortality for his pains. First, then, let me ask, how is a balloon, capable of containing 2000 feet of hydrogen gas, to be filled amidst the bustle and confusion which, I suppose (for I never was in such a situation), must prevail on the deck of a ship in a storm, and in the utmost peril of being lost? Admitting that in this confusion the rolling of the vessel, by which the apparatus is liable to be deranged, and that the rigging of the ship, &c. offer no obstacles to the process of filling the balloon, which I think, under these circumstances, next to impossible, how can the balloon be supported, while filling, against the fury of a hard gale of wind, which, if the balloon be made fast to the cask and the cask well secured, must tear it away in a moment? I am sure this must inevitably be the case. But, admitting the materials and fastenings to be sufficiently strong to resist the sweeping energy of the storm, how is the gas to enter when the sides of the balloon are collapsed so forcibly by the same powerful pressure? Would not the cask be in danger of bursting by the expansive force of the gas? INSTRUMENT FOR MEASURING HEIGHTS. Now for the fuse! How is it to be prevented communicating fire to the bydrogen gas, if, by accident, a little bending of the lower part of the balloon should take place, and bring the side of the balloon in contact with its fire? a thing likely enough to happen, particularly at starting, especially if the wind should happen just then to be very angry. In the next place, let me ask 217 Mr. Higginson how long time a balloon of the requisite size would require to fill it? This is important-would it be less than an hour? A serious time to people in momentary peril of their lives! If Mr. Higginson will answer these questions satisfactorily, he will very much oblige Hole in the Wall. AN OLD MOUSE. |