The watchmakers' hand book

485. To Regulate a Watch. Place the movement near to a regulator or watch indicating seconds, in such a position that the eye can easily observe the periodical return of an arm of the balance, as already explained, and commence to count, always starting from the instant at which the seconds hand points to zero. Then count steadily 1, 2, 3, 4, etc., until this hand reaches 30 seconds.

Assume, as is very commonly the case, that the balance should make 18,000 vibrations in an hour, or 150 in a half-minute, and that, on counting its vibrations, we find 65 double vibrations, or 130 beats, whereas it should give 150. It is thus 20 beats slow. Advance the index, and repeat the operation; and so on till the regulation is effected.

A greater degree of accuracy will be secured by counting for a longer period, say one, two, or three minutes; but when this is done, it is advisable, in order to avoid confusion, to recommence at one after each 30 or 50 have been counted, because all that is required is the final deviation.

Remarks. 1. All men are not equally quick of perception, so that, in counting and uttering the word one, it will be found to correspond with the end of the first beat in the case of some observers, and its commencement with others. By practicing on a well regulated watch, a watchmaker can determine to which of these classes he belongs. If to the second, he should double the one at starting; in other words, he should count thus:

1, 1, 2, 3, 4, 5, etc.

2. Advantage may be taken of the principle of the sounding-board by placing the watch on a sonorous body which will make the vibrations louder, or by placing between the plate of the watch and the ear a rod that is a good conductor of sound. By either or both of these means, the operation is rendered very easy, especially if the vibration counter recording the tens is employed.

486. Another Method of Regulating a Watch. When the movement is in going order, arrest the balance and make a mark with rouge on one arm of the escape-wheel. Release the balance when the seconds hand of the regulator crosses 60. Observing the number of revolutions that should be made by the escape-wheel in a given time (it would be six turns per minute with an ordinary 18,000 train), count its revolutions while the fourth wheel makes one complete turn; indeed, even this counting may be avoided by making a rouge mark on its edge where it corresponds with the mark already made on the escape-wheel. If after two or three minutes these two marks are found to occupy similar positions at the instant the seconds hand of the regulator crosses 60, the watch is to time. If there is any difference it is easy to ascertain whether this indicates a gain or a loss, and the index is moved accordingly.

487. To Regulate a Clock. The timing of timepieces by counting vibrations is much more easy than that of watches.

Before removing the pendulum count the number of its vibrations during two or three minutes. This time will be sufficient to afford a guide in regulating the clock after it has been repaired.

In most modern timepieces the escape wheel makes 120 revolutions in an hour, or two in a minute. Hence we have two modes of timing.

(1). Having made a light mark on the circumference of this wheel opposite to a fixed point, observe if the coincidence is maintained after intervals of two or three.

(2). Multiply the number of the escape-wheel teeth by 2, and the product by 120. This gives the number of oscillations the pendulum should make in an hour. Thence deduce the number it should make in two minutes, or the number per minutes can be obtained by multiplying the first product by 2, and it only remains to count the number actually performed in any definite interval.

488. Guilmet’s Synchrometer. When a clock is to time, its pendulum makes a certain definite number of oscillations per minute, dependent on the train. If, therefore, before taking it to pieces a comparison pendulum be set to make the same number of oscillations as that of the clock, or if the former be set to make the number which the train shows that the clock pendulum should perform, it can be used as a term of comparison for setting the clock to time after it has been cleaned. This is the principle on which the synchrometer is based. A pendulum is lightly supported on a frame, and has an adjustable rod sliding in a tube, and graduated so that it can be firmly set without difficulty to give the various periods of oscillation commonly met with in timepieces. The pendulum is hung freely without any train to drive it, and continues to oscillate for two or three minutes, quite long enough to ascertain whether agreement is maintained between the two pendulums.

489. Other Methods of Regulating a Clock. Various plans have been recently proposed for rapidly timing a clock, all based upon one idea: namely, the temporary addition of a seconds hand for purposes of observation. That suggested by M. Jacomin is recommended by its simplicity.

Having removed the pin and washer that maintain the minute hand in position in an ordinary timepiece, replace them by a light brass cap that can be fixed by a screw or in any convenient manner, so that a fine steel pin projecting from it shall be accurately in the axis of the minute wheel. Part of a watch movement, comprising only the center, third and fourth wheels with seconds hand attached, is supported in front of the clock dial, so that this pin can be inserted in place of the set-hands arbor, and it is evident that, if the clock is to time, the seconds hand should perform one revolution per minute as it will form part of the clock train. The length of pendulum must then be varied until this condition is found to be satisfied.

TIMING IN POSITIONS.
HORIZONTAL AND VERTICAL.

490. To adjust a watch so that it has the same rate when first placed in a horizontal and then in a vertical position is a delicate and often difficult operation; thus it is seldom found to be properly done in ordinary watches.

The rates in a vertical and horizontal position are made identical or nearly so by equalizing the resistances that interfere with the motion of the balance in the two cases, and by taking advantage of the displacement of the center of gravity of the balance spring.

Satisfactory results will be obtained in most cases by employing the following methods, either separately, or two or more together, according to the results of experiments or the rates, the experience and the judgment of the workman:

1. Flatten slightly the ends of the balance pivots so as to increase their radii of friction; when the watch is lying flat the friction will thus become greater.

2. Let the thickness of the jewel-holes be no more than is absolutely necessary. It is sometimes thought sufficient to chamfer the jewel hole so as to reduce the surface on which friction occurs; but this does not quite meet the case, since an appreciable column of oil is maintained against the pivot.

3. Reduce the diameters of the pivots, of course changing the jewel-holes. The resistance due to friction, when the watch is vertical, increases rapidly with any increase in the diameters of pivots.

4. Let the balance spring be accurately centered, or it must usually be so placed that the lateral pull tends to lift the balance when the watch is hanging vertical. In this and the next succeeding case it would sometimes be advantageous to be able to change the point at which it is fixed; but this is seldom possible.

5. Replace the balance spring by one that is longer or shorter but of the same strength; this is with a view to increase or diminish the lateral pressure in accordance with the explanation given in the last paragraph.

6. Set the escapement so that the strongest impulse corresponds with the greatest resistance of the balance.

7. Replace the balance. A balance that is much too heavy renders the timing for position impossible.

8. Lastly, when these methods are inapplicable or insufficient, there only remains the very common practice of setting the balance “out of poise.”

If there is a gain in the vertical hanging position of the watch, slightly reduce the lower side of the balance; the oscillation will increase somewhat in extent, and there will be a losing rate in this position.

The converse must be done in the opposite case.

When the vibration exceeds a whole turn, the changes will be the reverse of those above indicated. This fact must not be forgotten, especially in regard to the duplex and lever escapements, which may at first make a vibration of more than a turn, and subsequently less, according to the state of the oil.

We would again observe that the timing of a watch for position presents some difficulty, and it will only be after making a number of trials that the watchmaker will be able to accomplish it with certainty.

NOTE ON THE PROPORTIONS OF BALANCES.

491. Two very important elements in the timing are the weight and dimensions of the balance; it is, then, necessary that a watchmaker should practice himself in observing their relative values, and the effect of increasing one at the expense of the other on timing, and more especially on timing for positions.

The sensibility of a balance to variations in the motive force, and the time that elapses between the initial short vibration and the first that is of normal extent, a time that is approximately constant will serve as criteria. A balance that is very sensitive to variations in the motive force is generally too small; and one that attains to the normal arc of vibration almost instantaneously is, as a rule, too light. The converse effects would indicate that the size and weight were excessive.

In order that he may be able to practically apply these remarks, the workman should gain experience by making observations on several watches whose rate is known to be good, in the following manner.

In regard to weight: Stop the balance at the position of rest of its spring, then release it and count the number of vibrations up to the point at which the normal arc is attained; the extent of this must have been previously recorded on the plate with rouge marks.

Record the number thus obtained in a table opposite to the dimensions of the balance, and, by comparing these dimensions with those of another balance of equal size, the weight can be ascertained and also recorded.

In regard to size: Pass through the center pinion a kind of short screw arbor carrying a large thin ferrule, on which a cord supporting a weight is coiled. Fixing the movement in a movement holder, set it in a vertical plane and observe the extent of the vibrations of the balance with different weights attached to the cord.

These arcs should also be recorded in the table opposite to the dimensions of the balance. With sufficient practice the watchmaker will be enabled to judge at a glance whether the weight and size are well proportioned.

DEMAGNETIZING.

492. The following method of removing the magnetism from a watch that has been accidentally brought under the influence of a powerful magnet is proposed by Professor A. L. Mayer. We shall not here enter more fully into the subject than is necessary to indicate the manner in which a watchmaker may restore the steel work to its original condition.

Take a delicately suspended magnetic needle, say a mariner’s compass, the length of which is about equal to the diameter of the watch, and lay it on a table. Now place the watch to be operated on, which should not be going, on the table close to the needle and on either the east or west side of it, having previously turned the box around until the needle points to zero. Taking care not to vary the distance between the centers of the watch and compass, observe the number of graduations to which the north end of the needle is deflected with each figure on the dial brought in succession nearest to the compass; it is also necessary to note whether the deflection is towards the east or west.

For example, assume that the watch is on the east side, and that, with noon nearest to the compass, the north end of the needle is turned 12° to the east, that is, towards the watch. This shows that some point in the watch in the neighborhood of the number XII on the dial possesses what is known as “north polarity,” and if the deflection had been to the west the polarity would have been “south.”

493. To take an example. Let the results of a series of trials with the several hours in succession towards the compass be as given in the following table:

It will be seen that the greatest deflection westward corresponds to three o’clock, and, in the easterly direction, to eleven o’clock. This shows that the strongest south and north polarity are respectively in these directions. The first thing to be done is, then, to eliminate this particular magnetism. Placing a bar magnet in a horizontal direction, approach the watch to its south-seeking end in such a manner that a line X X′, Fig. 228, through the axis of the magnet, will pass through the center C of the watch, the figure XI, which marks the point of extreme north polarity, being nearest to the bar magnet. Now cause the watch to oscillate so that it alternately takes up the two positions A and B, and, when this has been several times repeated, bring III in a similar manner near the north-seeking pole of the bar magnet, oscillating the watch in the same way. Again try the watch with the compass, repeating the above operations if necessary until the readings are somewhat as follows:

These figures show that, in counteracting the polarity at III and XI, the magnetic action of the watch in all other positions has, as might indeed have been anticipated, materially diminished. Such a condition of things will, of course, not be attained at once, and it may even happen that the polarity at the two points III and XI is reversed; in such a case it is only necessary to oscillate the III in front of the south-seeking pole instead of the north.

The last table shows that a maximum south polarity is now at V, and north at I. These points must therefore be operated upon in the same manner, and, by proceeding in this manner, and successively eliminating the worst points, the magnetism may be effectually removed.

As proving the efficiency of the above method, Prof. Mayer mentions a case in which a watch lost one hour in six in consequence of magnetism, and yet after the above treatment, it resumed its original rate of about a second per day.

494. Another Method. A second method of procedure has recently been described by H. S. Maxim. He employs a specially arranged apparatus, based on the principle that if a watch or other object be subjected to rapid alterations of magnetism, while gradually withdrawing it from the influence of the magnetic poles, the distance ultimately becomes so great that the reversals are inappreciable, when the watch is found to be demagnetized. A bar magnet is arranged to revolve in a horizontal plane around a vertical axis; the watch being placed in a small pocket opposite to the magnet, is caused to rotate in an ever-shifting vertical plane, while the frame supporting it rotates in a horizontal plane. While these movements continue the watch carrier is gradually moved away from the magnet by the action of a long horizontal screw, and it is stated that watches that have been completely spoiled can be rendered perfectly free from magnetism by such an apparatus.