NUMBER ONE.
Twenty-five years of hard labor amidst the dust and din of machinery, with hands cramped, and fingers stiffened by the continual use of tools, and with a brain constantly occupied in ringing the changes upon wheels and levers in their almost infinite combinations,—it requires a degree of courage to undertake to write anything that can be dignified with the name of an “article,” although it does propose to treat upon a subject with which we are fairly familiar; but it is consoling to think that one is not expected to write for the pages of this practical journal with the same degree of elegance and polish that should grace the columns of a review or magazine; that we can appear here as plain, practical mechanics, and use good hard, round words to express our ideas, backed by an experience which should add some weight—and we welcome the appearance of the “American Horological Journal,” which is to serve a good purpose by bringing out the actual experience of men who have grown gray in the art and mystery of clock-making, and preserving, by means of the “art preservative of all arts,” their dearly bought knowledge and experience, for the benefit of those who in their turn shall follow them; and it will also benefit the people in general by giving information that will lead to the purchase of good and tasteful clocks for household use.
That such a journal is needed to enlighten us, is made plain by the fact that in almost every newspaper we have a vivid account of some wonderful clock “recently invented,” which may possess some merit, but they are so grossly exaggerated by some ignorant “penny-a-liner,” that we are almost led to believe in the Irishman’s marvellous “eight-day clock, that actually ran three weeks.” Even the proverbially correct “Scientific American,” of which I am a constant reader, has in its issue of June 19th, an account in its “editorial summary” of a clock in France containing “90,000 wheels,” and perhaps the most curious part of the mechanism is that which gives “the additional day in leap-year,” etc. Now, it will require but little knowledge of clocks to tell us that one with 90,000 wheels was never made and never will be, but “the additional day in leap-year” has been given by calendar clocks in this country since the year 1853.
It is not proposed in the series of articles to follow, to discuss the early history of clocks. Reid and Dennison have written enough to convince the most skeptical that the clock is an old invention. It is not important to us who invented the pendulum, or this or that escapement, but who makes the best pendulum, the best escapement, the most perfect train of wheels and pinions. These are vital points, and we shall endeavor to give them that attention that their importance demands. It is proper to state here that any assertion made, or rule given, has been tested, and is the result merely of our experience, and we do not claim that it is all there is of the subject; for we are aware that the experience of others may have led to results entirely different; but if all clock-makers will avail themselves of the columns of this journal, we shall not only become better acquainted by an exchange of ideas, but better clock-makers.
The subject of wheels and pinions is of the greatest importance in clock-making, and the utmost care and skill are required to execute a train which shall not only run with as little friction as possible, but the friction must be equal; for if there is no variation in the train force, the escapement and pendulum will always be actuated by the same amount of power, and the performance of the clock can be relied upon. Clock text-books do not fully impress this subject. We find a great deal upon this or that escapement, and the different pendulums. Dennison has a couple of pages full of abstruse calculations upon a method of shifting an extra weight upon a rod, so that the going of a clock can be varied one second per day; but if his wheels and pinions are not perfect, a large tooth here and there will vary the clock more than that.
Reid overawes us with his knowledge of the proper curves of the teeth of wheels; but it must have been only theory, for his practice was to saw his teeth, and his cycloids, epicycloids, and hypocycloids were left to the mercy of the “topping file” in the hands of his “wheel teeth finishers,” instead of shaping up the teeth in the engine, as is done now. We have generally cut the wheels of fine clocks over several times with different cutters before taking them from the engine; the last cutter having but one tooth, which can be made perfect as to cut and shape, and, running with great speed, will leave the teeth the proper shape, very smooth, and as true as the dial of the engine. Escape wheels, especially, require great care in cutting, as the teeth for dead-beat escapements are somewhat long and thin; the least inaccuracy is certain to cause trouble. It is absolutely necessary that the dial plate of the cutting engine should be perfectly true, with clean, round holes, and a perfect fitting index point, with a cutter arbor without end play or lateral motion—these are the essentials of a good cutting engine, without which a good clock cannot be made.
We have generally made a practice, upon the completion of the train for a fine clock, to put in the place of the escape-wheel a very light, well-balanced fly, to prevent “backlash,” and a very fine soft cord on the barrel; then hang on a very light weight; so slight that—all of the wheels being balanced, and no oil upon the pivots—the fly will move so slowly that its revolutions may be counted. By taking care that the weight be not too much in excess of the resistance, the least inaccuracy in the wheels and pinions may be discovered by the difference in the velocity of the fly, or by its suddenly stopping, which will be occasioned by any inequality in the train teeth, which would not have been discovered by the closest scrutiny. It was by means of this test that we discovered an inaccuracy in a pinion, caused by hardening, which could not have been discovered by a less delicate test.
The wheels in the train should be as light as possible, for as the whole train is stopped every time a tooth drops on the pallets, it is plain that the driving weight must overcome the inertia as well as the friction of the train at every beat. To this end it has been customary to “arm out” the wheels, leaving a very light rim supported by light arms, the wheels being generally of cast brass, turned up, and cut, then lightened. We followed this plan for some time, but abandoned it, as we found great difficulty in making a perfectly round wheel. The arms serve as posts to support the rim in cutting or turning, but the space between is very apt to spring down. We prefer making the wheels of fine hard-rolled sheet brass; it is superior to cast brass, much finer, harder, and more durable, and is freer from flaws. After the wheels are cut, they are turned out on each side, leaving a thin web in the centre; they can be made lighter, finished easier, and are round.
As to the shape of the teeth in clock-wheels, the subject has been so ably treated by Reid, Dennison, and Prof. Willis (who has invented an instrument to assist in laying out the curves for the teeth of wheels), that we shall not attempt it in this paper; besides, there is so little of the entire theory that can be applied to a clock-wheel of two and a half inches in diameter, with 120 to 140 teeth, farther than to leave the wheel and pinion of the proper diameter, that we consider it unnecessary; for if makers of regulators and other fine clocks will use pinions of 16 or 20 teeth, the friction or driving is all after the line of centres, and the whole subject of cycloids, epicycloids, and hypocycloids is reduced to a very small point, and might be said to “vanish into thin air.”
Having given only a few practical hints, and not yet crossed the threshold of the subject, we propose to continue from month to month—if the readers of the Journal do not weary—the discussion of the various parts that go to make the sum total of a fine clock, with notices of the various clocks made in this country.
It certainly comes within the province, and is the duty, of a journal devoted to Horology, to make a note of any and all the new improvements that pertain to the science. We give, then, some few, the merits of which have struck us as being a very important matter of consideration.
The best clock time-keeper is not absolutely perfect, so its rate must be kept; but the watchmaker ordinarily has no means of correcting the error of his regulator, until the accumulation renders it a serious inconvenience. Did he possess a Transit instrument, properly set and adjusted for meridian, together with the required books and knowledge of observing, he could from day to day correct his clock and keep accurate time; but these are all expensive, as well as involving time and labor. Suited to the wants of the artisan is a little instrument called the Dipleidescope; simple in its construction, and not liable to get out of position or order, it forms the best substitute for the transit we have seen. It is founded on the theory that the double reflection from the two surfaces of planes at an angle of 60° will coincide when the object reflected is in a true line with half the base of the whole triangle. Having a prism cut in an equilateral triangle, one angle is set directly down toward the centre of the earth, the base being brought parallel with the line of the horizon. Now, if the axis of the prism is in a line with the meridian, a reflection of the sun will appear, at the instant of crossing the meridian, on itself—that is, there would be but one image. If the instrument is well made, there can be no doubt of its accuracy and value to those who, wishing to verify their time, are not situated so as to use a transit.
Another improvement is a Bench-Key for watchmaker’s use. No one who has had any experience at the bench but will appreciate an article that facilitates the setting of time-pieces for his customers. In winding, it is equally valuable. It is not dependent for its strength of torsion on the spring-chuck principle, the power being applied close to the square by means of a pin that passes through the key.
Hall’s Patent Cutting Nippers are a positive desideratum; a large wire can be cut off without the least jar to the hand, the leverage is so great. The smallest sizes are suitable to the ordinary run of watch-work, and can be used in clock-work better than any cutting-plyers extant. Strong and durable, they possess one quality that all watchmakers will appreciate—if a cutting-jaw is broken it can be replaced by another.