PART III

.

HEALTH AND MANIPULATION.

PRESERVATION OF HEALTH.

=217.= Some of the following directions may perhaps be considered to be over-minute and too restrictive; but they are not so. Good habits contracted in youth are easily maintained, and, when the watchmaker has tried them long enough to convince him of their influence on his health, he will experience no difficulty in keeping them up.

THE SIGHT.

=218.= When working at any small mechanism, such as a watch, it is necessary to use the glass, but this practice is apt to produce inflammation of the conjunctiva or cornea and a weakening of the eyesight; a too frequent and prolonged use of the glass will have the same effect as using spectacles that are too strong.

In order to preserve his eyesight, the watchmaker should take the following precautions:

He should not retain the glass at his eye by a contraction of the muscles for more than a brief interval of time. The glass holder, which can be at once set in any desired position, has therefore much to recommend it.

Drill a few holes in the frame of the glass to avoid or at least diminish the inconvenience that arises from the heating of the enclosed air, as well as from the deposition of moisture on the surface of the glass.

Do not use glasses of too great magnifying power; they needlessly fatigue the eye.

Only use glasses that are truly achromatic. If compelled to use the ordinary simple glass, place a ring of dead black paper inside the frame and against the lens, which, by diminishing the field of view, will reduce the inconvenience due to spherical aberration.

It is hardly necessary to advocate the use of a green cardboard shade to the lamp, as they are so generally used by watchmakers. It should be so arranged as to protect the head and eyes from radiation, and cardboard is preferable to metal as it radiates less heat.

Working at night and by artificial light, more especially by the dazzling light of gas, fatigues the eyes much more than with ordinary daylight, and the workman will find it a relief, if obliged to work by artificial light on very minute objects, to rest his eyes frequently on large stationary bodies. If he can do so, it is a great comfort to bathe the eyes in cold water.

It is good practice to habituate oneself to the use of either eye with the glass.

By adopting these simple precautions, how many of our fellow-workers who are now only able to see objects indistinctly and suffer from incipient blindness would have preserved their sight uninjured. And there is yet another precaution that has been pointed out by Dr. Haltenhoff, of Geneva. He has shown that by avoiding an excessive indulgence in alcoholic drinks or tobacco, many old watchmakers in that town have succeeded in preserving their sight unimpaired, and it is impossible to doubt the truth or over-estimate the importance of this fact.

The same authority draws attention to the necessity of taking care that, before adopting watchmaking as a trade, youths should ascertain that they do not suffer from progressive nearsightedness, which is often hereditary, as in such a case they would most certainly be compelled to abandon it in after life. Boys should not be set to work on such small objects as the details of a watch too early in life, before the membranes of the eye have assumed a certain degree of rigidity.

Mr. Brudenell Carter, a well-known ophthalmist, is of opinion that the habitual use of the glass by watchmakers has the effect of actually developing and preserving the power of the eye.

THE BODY IN GENERAL.

=219.= It is often found that an old, or even middle-aged watchmaker is irritable, often tired and soured. This arises, not so often from an over-excited uneasiness in regard to his trade, an explanation that is usually urged, as from a derangement of his digestive organs brought about by the habit of life he is compelled to adopt. Prolonged working at minute horological mechanism is perhaps more wearying to the mind and body than any other trade or occupation.

To avoid its ill effects the watchmaker should adopt the following precautions as far as possible:

Do not use a stool with a stuffed seat, but prefer one of cane or wood.

Take care that the relative heights of the board and stool are such that an excessive compression of the muscles of the chest, etc., is avoided during any long operation that renders it necessary to maintain the body in a constrained position.

A stool with adjusting screw similar to a music stool is convenient from this point of view.

Change the position as much and as often as possible, especially when working with the file or graver. With this object in view many workmen have a second board of such a height that they can work standing.

When using the lamp let it always be provided with a cardboard shade as already recommended.

A screen to protect the head from the direct heat of the flame is often found advantageous; in fact, the watchmaker should adopt the advice of Boerhaave: “Keep the head cool and the feet warm.”

Let him always remember that nothing does more harm than sitting to the bench immediately after a meal. He should allow an interval of half an hour to elapse and with some temperaments, even this is not enough; during this period he should only do work at which it is possible to stand. A little exercise, such as a walk that is not hurried, will be still better; it will stimulate the circulation and stretch the muscles that have been maintained in a constrained position for a long time through the prolonged attention and slight motion that his labors involve.

USE OF THE FILE AND GRAVER.

=220.= The first operations that a watchmaker ought to learn are to file flat and square, to turn round, to forge, to hammer-harden a piece of metal without deteriorating it. These accomplishments are but too much neglected in the modern training of an apprentice, an omission that is partly owing to the want of good instructors and partly to the shortness of the time he can afford to devote to learning his trade.

TO FILE FLAT AND SQUARE WITH BOTH HANDS AT ONCE.

=221.= It is a very common practice to place an old file in the hands of an apprentice, to fix in the jaws of a vise a piece of metal, either brass, iron or steel, and to set him to work rubbing and filing the surfaces with great labor, the only result being that they are utterly mis-shapen and covered with brilliant spots.

This method is bad. The action of the file is mechanical and the problem that has to be solved is the following: To produce good work in the shortest possible time, and with the least expenditure of force. It is therefore only by very slow degrees that an apprentice can hope to acquire the requisite ability, if he is set to work trying to shape an object in some hard metal before he knows how to maintain lines straight and surfaces flat. Not knowing how to proportion his effort to the resistance to be overcome, and allowing the file to travel irregularly over the surface, he gets confirmed in the tendency to give a rocking motion to the file, whereby the surface is left round, and he will find it all the more difficult to throw this habit aside.

It is far better to let him commence on round pieces of common wood, filing with a rasp or coarse-cut file, without removing too much at once. By this means he may rely on learning to file flat and square by the eye alone without the aid of a straight-edge.

When he works well in common wood, he can be set to file harder woods, box for an example, roughing with a rasp and finishing with a new bastard file. He should not be allowed to have hard wood until able to file a surface so well that, on placing a metal rule across it in any direction, it is found to be flat.

=222.= Let him then advance to brass, which, if cast, should be previously dipped in acid to remove the hard surface, as this should not be filed off. The resistance it offers would cause a jerky motion of the file that would be apt to disturb the slight amount of decision the hand has already acquired.

As brass opposes a considerable resistance, the pupil should be carefully watched with a view to preventing too rapid movement and an excessive pressure, involving waste of power, while he fancies the work is being proportionately advanced; the manner in which the file is applied to the surface should also be observed, taking care that little or no pressure is applied during the backward stroke. The teacher should both explain and demonstrate that the main secret of success consists in a perfect equilibrium between the actions of the two hands; one should increase as the other decreases with the horizontal motion of the file, since the two levers in use, namely the portions on either side of the point of contact, are continually the one increasing and the other decreasing.

By filing steadily and attentively, the hands will gradually acquire the requisite sensitiveness, or tact, that enables each to adjust the pressure in proportion to the other, as well as the knack that enables them to maintain the surface flat. It is important to avoid short and jerky movements.

Practical instruction from a competent teacher must be relied on to complete the directions here given; no written instructions can replace it.

It is advisable to use new, or nearly new files in the above lessons; the wear will have brought them into good condition for working iron or steel.

Proceed with these metals as already explained in regard to brass, and special attention must still be given in order to prevent hurry on the part of the pupil. The files remove less metal at a time and a greater pressure is necessary, so that he does not make such rapid progress as with brass, and this gives rise to a tendency either to use new files, which are soon spoilt, or to give the stroke too suddenly, while applying considerable pressure, especially during the return stroke. He thus heats his file, breaks off the crests of the teeth, which become embedded in the metal and do much to further damage the file. Moreover, he will lose some of the sensitiveness of touch that his hand has already acquired.

=223.= It would perhaps be well to subdivide the day into three parts for as long as appears necessary; the first to be devoted to filing, the second to turning, and the third to forging and cold hammering.

By this means he will be quicker in acquiring the requisite skill of hand and eye, and, when he has attained to this ability, it will be time to practice himself in the management of various tools. Feeling certain of himself he will soon become quick in his work.

It is prejudicial to the true instruction of a pupil and a false economy of both time and money, to let him commence either a clock or watch before arriving at this point. He will experience difficulty in making even the simplest pieces, which, besides being very badly made, will take up a long time; he will keep forgetting as he goes on, because, owing to the slowness with which he works, the construction of a machine occupies months, or even years, whereas it would only have occupied a few weeks, or months, if he had possessed sufficient manual skill to enable him to handle properly the file and graver.

We insist specially on the need of this preliminary training of the young horologist, because, with very rare exceptions, if a pupil is set to delicate details before he is master of his tools, he works with a want of decision, and, therefore, with difficulty. He will, as a rule, make a workman of but moderate ability, and will soon become disgusted with his trade, from the mere fact that he cannot work with ease and rapidity.

Time is an element of success; hence gratuitous apprenticeships for short terms, that become a tax on the master if he does not soon make use of his pupil’s services, will very seldom produce good watchmakers.

TO FILE FLAT WITH ONE HAND.

=224.= When an object is to be held on a cork or wood block fixed in the vise, with one hand, and filed with the other hand, special care must be taken to lay the file flat without any hesitation after each return stroke, and the hand should be able to feel if the file is wrong in this respect, and to at once bring it flat. After the pupil has learned this, he will very soon be able to adjust the pressure and the force exerted in moving the file horizontally, so that it shall remove an equal amount from the entire surface operated upon. It often happens that the object can conveniently be rested upon a finger of the left-hand while the right-hand holds the file. The maintenance of the file flat is in that case much easier.

=225.= _Mechanical device for filing flat._ This (the _pradel_) consists in placing behind the workman a horizontal bar, on which rests one end of the file handle, prolonged for the purpose to about a yard in length; thus the file has two points of support: the bar, adjusted at a convenient height, behind the workman, and the object to be filed flat fixed in the vise in front.

This method, while convenient for amateurs, may be utilized in teaching an apprentice, letting the supports be hinged at one and press at the other end on a rather strong spring index, which must be prolonged so as to be brought under the eye of the pupil.

The displacement of the index will show him every false movement of his hands, and will guide him in adjusting them. It would be best if the prolongation of the handle were as light as possible, but rigid and arranged so that the file can be held naturally.

TO TURN CYLINDRICAL PIVOTS, ETC., AND SQUARE SHOULDERS.

=226.= Just as in working with the file, advice and demonstration by a good master are here indispensable.

The materials should be worked in the same order as is explained in parts =221-4=; that is: wood, brass, iron, steel, hardened and tempered steel; no one sample being set aside until the student can turn it perfectly round, flat on shoulders, etc., and smooth throughout.

He should turn for a long time, whether it be by the lathe or bow, exclusively with the point of a square, or lozenge-shaped graver, the end of which is ground off on a slope; this is the only possible method of learning to turn true, and it enables the workman to acquire great delicacy of touch.

Owing to carelessness, or to the fact that, when first beginning, they were set to work on metal that was too hard or rough, most learners turn with gravers that are ground to very blunt points; as the graver bites less, they are obliged to apply a proportionately increased pressure, and only succeed in tearing the metal away, subjecting it to a kind of rolling action, and rendering the hand heavy. If a pupil will not practice turning with the graver point, so as to preserve it intact for some time, dependent on the nature of the metal, he will never be able to turn perfectly true.

The bow should be used through its entire length, and with a motion that is progressive, not jerky. The knack of the turner with the bow consists mainly in keeping the simultaneous actions of the two hands quite distinct; one drawing the bow downwards, while the other depresses the point of the graver supported on the =T=-rest, and these two movements of the hands must be performed at the same time, but quite independently.

Irregular and sudden depressing of the graver point, or engaging it too deeply, causes its frequent rupture. This also sometimes arises from the fact that the point is not removed with sufficient rapidity, so that on raising the bow the metal catches it while traveling in the reverse direction; the graver is thus drawn slightly towards the work, and its point will be found too close in when the bow again descends.

As has been already observed, the bow, which must not be too short, should be used to its full length with a regular, but not rapid motion. Afterwards, when the hand has learnt how to manage the graver, the speed can be gradually augmented. There is always a danger of losing time, teaching, and, therefore, money, if pupils are too much hurried in their lessons. Before trying to work quickly, they should, at any rate, know how to work fairly well.

Short and sudden movements of the bow will make the object turned jerk; it will be heated, and the sharp angles of the graver will jamb in the metal; thus there is less work done, although there is more noise, and this is done badly.

=227.= When sufficient experience has been gained in turning with the graver point, and a trial is made with the cutting edge, do not attempt to remove much at a time by pressing heavily, but take the metal sideways so as to remove a continuous thread, using all the points of the edge in succession and the entire length of the bow. The metal will thus be removed as a thin ribbon or shaving. When the hand has had some experience, it will be found easy to remove long strips, and the work can be done quickly, although there be no hurrying in the movement of the bow. These remarks are equally applicable to turning with a lathe.

=228.= Hardened steel that has been let down to a blue temper requires certain precautions. If the graver is found not to cut cleanly, it must at once be sharpened, and no attempt should be made to remove more metal by increasing the pressure of the hand, because the steel will burnish and become hard under a point or edge that is blunt, and the portions thus burnished are sometimes so hard as to resist the best gravers. The only way of attacking them is to begin at one side with a fine graver point which must be sharpened for each stroke; at times it becomes necessary to temper the metal afresh before it will yield. It is asserted that by moistening the point of the graver with petroleum it becomes more able to attack hard substances, and that a mixture of two parts petroleum and one part turpentine enables it to turn very hard steel with comparative ease. Indeed, for all turning it is a common practice to moisten the graver with oil, water, turpentine, or simply by introduction into the mouth.

We have frequently seen apprentices, and even watchmakers, themselves, careless as to the proper sharpening of their gravers and thinking that they could hasten their work by the application of considerable pressure; they thus produced bright spots that required several hours of work before they could be removed.

There is one essential condition for ensuring good work with the lathe, and this consists in the perfect roundness of the points or holes of the runners or centers, and of the holes or points that are supported in them; this perfect truth is nevertheless very rarely met with, for it is noticeable that barely one watchmaker in ten knows at the present day how to roll such a point. We shall subsequently indicate the precautions to be observed in order to secure this accuracy.

The diameter of ferrule is also to be considered; if it is too small, the bow will slip and the object will only rotate by jerks; if too large, it loads the object unnecessarily and the velocity of rotation is reduced, since for the same stroke of the bow the ferrule must make a less number of turns. Moreover, if it is of large diameter, only a light bow must be used, because otherwise the force applied would be excessive.

Swiss workmen—at least the great majority of them—turn with the right or left-hand indifferently. This is a very useful accomplishment easily acquired when young.

The working of various tools, such as the English or Geneva mandrel, and any lathe driven by a treadle, will be a great help in developing the sense of touch and in making it more certain.

But it must not be forgotten that, in order to turn well, the lathe must be well made and planned; without this, no accurate work can be done. The lathe is the first and most important of tools, and a great number of very serviceable accessories can be added to it, which, unfortunately, but few watchmakers know how to make properly. As a rule they content themselves with a simple pair of finishing turns on which but a comparatively small amount of work can be done.

Without committing the mistake of having a too great multiplicity of tools, let the pupil rest certain that a well-planned set of tools in good condition both facilitates and abridges his work and renders it more perfect.

##