“ However accurate an instrument for the mensuration of time may be, it would be of little use for close observation unless we have some standard by which to test its performance. We look to Astronomy to furnish us with this desideratum, nor do we look in vain. The mean sidereal day, measured by the time elapsed between any two consecutive transits of any star at the same meridian, and the mean sidereal year—which is the time included between two consecutive returns of the sun to the same star—are immutable units with which all great periods of time are compared ”

“ But for a spheroid in rotation the centrifugal varies by the law of mechanics, as the square of the sine of the latitude from the equator, where it is greatest, [Pg 10] to the poles, where it is least. And as it tends to make bodies fly off the surface, it diminishes the force of gravity by a small quantity. Hence, by gravitation, which is the difference of these two forces, the fall of bodies ought to be accelerated from the equator to the poles proportionably to the square of the sine of the latitude, and the weight of the body ought to increase in that ratio. ”

“ Well made as to truth of centring, of division, of form of leaves, and polish, are, as the trade well knows, of vital importance to the value of the time-piece.
The making and finishing is one of the most troublesome, as well as most expensive of all the processes in watch work. The nature of the material renders it difficult as it approaches so nearly in hardness to the tools used in cutting. In the ordinary Yankee clock, the lantern pinion has entirely superseded the solid leaf, which substitution was the greatest element of success in their cheap construction. ”

“ 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. ”

“ The rotation of the earth is held in its own plane by its own revolution, the same as the gyrascope seems to overcome the laws of gravitation by its force of revolution.
But not only do the sun and moon disturb the plane of the ecliptic, but the action of other planets on the earth and sun is to be taken into account. A very slow variation in the position of the plane of the ecliptic, in relation to the plane of the equator, is observed from these influences. It must be remembered that a very slight deviation in the angle can and would be detected by observation with modern instruments. ”

“ We have not the time to learn by self-experience all the boasted usefulness and capacities of the tool; so we go back to our old verge or Jacot lathe when we have to put in a pivot or a new staff. We may know all about the escapement and be able to detect the cause of any trouble with it, but we have no knowledge of the latest modes of repairing the injury when it is discovered, and this knowledge is what I hope to find in your journal. I live in a section where the general class of work is of a very low grade, even the old verge being very common. ”

“ Now the attraction of an external body not only draws another to it in its whole mass, but, as the force of attraction is inversely as the square of the distance, it follows that the attracted body would be revolved on its own centre of gravity until its major diameter was in a straight line with the attracting body. ”

“ Thus, the question, what is a foot? is more difficult to answer than at first sight appears. Many years ago the French perceived the difficulty appertaining to the national standard, and they, therefore, decided that a metre should be the ten-millionth part of one-fourth of the earth’s circumference—that is, ten-millionth of the distance from the Equator to the Pole. ”

“ 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 [Pg 16] better acquainted by an exchange of ideas, but better clock-makers. ”

“ 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 will be readily seen that this precaution will become more important as we recede from the equator; for if we were to suspend a pendulum at the pole in a true line with the axis of rotation, and if the plane of vibration remained constant, the earth would turn once around that plane in the diurnal period. During this time there would be a continuous torsion on the point of suspension, that would in time materially affect the accuracy of the instrument. The reasoning holds good for every latitude—degree of influence being the only difference. ”

“ 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 must premise that the whole theory of taking time by sidereal observations is based on angular motion, the mensuration of one of the angles of motion giving a measurement of space, so that to say space, or distance, is equivalent to saying time. From noon of one day to noon of another is the whole problem to be solved by correct division. ”

“ At first sight, it seems difficult to admit that the relatively small proportions of aluminum which enters into the composition of this bronze can be sufficient to modify so extraordinarily the properties of the copper which constitutes so large a portion of its weight. But we must remember that the specific gravity of aluminum is very low, and that a given weight of this metal possesses a bulk four times as large as the same weight in silver. It follows from this that the ten per cent. of aluminum contained in the bronze equals in bulk forty per cent. ”

“ The length of a seconds pendulum oscillating in a certain latitude has been our method of obtaining a standard; but this also has its weak points, so that to obtain a constant standard it is necessary to have some pattern which is unchangeable, and thus a metal has been chosen that expands or contracts but little either with heat or cold; and this, at a certain temperature, is the standard measure, and such a standard may be seen on the exterior wall of Greenwich Observatory. ”

“ There is this advantage in the lunar theory, that it takes the earth as a whole, disregarding any irregularities of surface, or the local attractions that influence the pendulum—the difficulties of measuring an arc of the meridian being an obstacle to perfect accuracy. ”

“ 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 ”

“ Whole nations have been swept from the earth, with their languages, arts, and sciences, leaving but confused masses of ruins to mark the place where mighty cities stood; their history, with but the exception of a few doubtful traditions, has perished ”

“ The dust that falls from the stones is preserved for the subsequent processes of grinding and polishing those facets that distinguish the many-sided brilliant from the dull, original crystal of the diamond. It is used, mingled with oil, on a flat iron disk, set revolving with vast rapidity by steam-power, the stone itself being held upon this disk or wheel by a tool to which it is attached by a mass of fusible metallic alloy, into which the stone is skilfully inserted. ”

“ 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. ”

“ Also, the difference between mean and apparent solar time was required to illustrate the use of the tables of equated time, the necessity of which will become patent when the use of the transit instrument for the establishment of time, or a fixed standard, is introduced. Also, the disturbing effects of the sun and moon collectively and relatively as to position, could not be passed, as they produce the precession of the equinoxes and the nutation of the pole—essential elements in the computation of time. ”

“ Taking the earth as a homogeneous mass, analysis gives us the certainty that if the intensity of gravitation at the equator be taken as unity, the increase of gravity to the poles eliminating the differences of the centrifugal force must be = to 2.5, the ratio of the centrifugal force to that of gravitation at the equator. ”

“ A very ingenious device is used for dividing the leaves under the cutter, which revolves at a moderate speed over a slide, carrying a pair of centres, between which the turned up piece of pinion wire is placed. The slide is now pushed up to and under the cutter, and in its passage as much of a cut is taken as is desirable; in drawing back the slide the fresh cut space passes under a flat piece of thin steel, screwed on the frame, and set at a slight angle to the axis of the centres. ”

“ Supposing a wheel of 60 teeth, depthing into a pinion of 8 leaves, it can readily be seen that the arc of the motion of the wheel tooth is of greater radius than that of the leaf of the pinion, and it follows that if the teeth and the leaves are made in taper form with straight sections, there must occur a sliding motion on the surfaces of both—the power thus absorbed being totally wasted; but if we curve the surfaces we may approach a form so nearly perfect that the wheel teeth, being motors, really roll on the leaves, avoiding almost entirely the friction caused by sliding ”

“ To all intents and purposes we remain as stationary as the oyster. Not only do we have these vexations, but the ignorance of the public at large as to the treatment of their time-keepers is a fruitful source of annoyance; we are often charged with fraudulent practices, and a certain degree of caution is observed by more than the most ignorant. ”

“ For watch or chronometer purposes the only really useful stones are sapphire, ruby, chrysolite, and aqua marine—all possessing peculiarities that deserve some remarks, as they are of the utmost importance to the hole maker. The sapphire is the hardest stone, next to the diamond, and yet specimens can be, and are found, so soft as to drag in polishing. ”

“ The various steps are all connected some way with diamond in its different shapes. “Bort,” the technical name for another variety, is merely fragments of the stone that have been cleaved off from a gem in process of cutting, or gems that have been cut, but found too full of flaws to become of use for ornamental jewelry purposes, the cost depending on the size, varying from $5.50 to $18 per carat. This “Bort” is used as turning tools—the larger pieces being selected and “set” in a brass wire and used on the lathe, in the same manner, and with the same facility, as the common graver. ”

“ The perpetual accumulation of facts at Greenwich, whether these be of an astronomical nature, or appertaining to the air we breathe and its subtle changes, is a proceeding that must eventually lead us on to a correct knowledge of the laws which govern these matters, and also keep us acquainted with any variations that may be occurring in the elements that surround us. ”

“ Isolated as we are, we (the country village watch repairers) have few means to improve our knowledge of the trade, but work on the same old principles learned when we were boys and apprentices, and of better and more expeditious ways of doing our work we are entirely oblivious. True, our friends of the Hebraic persuasion, who, angel like, bring us face to face with the outer horological world by selling us material and tools, occasionally present to our benumbed vision something new, such as a Swiss lathe, or lathes used in the factories ”

“ The form of diamond most in use for mechanical manipulations, is almost always crystallized; yet it will be seen that the agglomerated form of diamond carbon plays no unimportant part in jewelling. As a jewel, no use is made of the diamond, other than as an end-stone. Marine chronometers, in which the balance will weigh from five to nine pennyweights, are almost invariably furnished with a diamond end-stone, set in steel. Yet, hard as the substance is, it is often that a pivot will cut an indentation in its face. ”