Page:Popular Science Monthly Volume 46.djvu/75

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The essential difference between the American manner of making a watch and the Swiss is brought to mind in the course of your stay in this room. Take the lever in illustration. The PSM V46 D075 An american watch lever.jpgFig. 3.—An American Lever. American manufacturer cares little how a lever looks, provided only it serves its purpose properly. The Swiss workman, however, must needs dress down the lever until it shall have a delicacy and comeliness all its own. The difference between a Swiss and an ordinary American lever has been likened to that between an antelope and a bear (compare Figs. 3 and 5).

Having remained in the escapement room long enough to master the principles and the practice required for making those delicate and critical parts the boy, or rather young man—for he has added several years to his age by this time—is ready to enter the last or timing room. Here he learns to do the very fine work which makes a watch a fine timekeeper. Without this work a watch may run a little faster when wound up tight than when partly run down. It will often run a little faster in the cold than in the warm pocket. It may not keep quite the same time when hung up that it does when lying down.

To get rid of all these imperfections requires very careful, patient, and skillful work. It will suffice for the ordinary reader if we give but a few suggestions as to the manner of procedure.

The tendency of a watch to vary by reason of the varying pressure of the mainspring is overcome by means of the hairspring. Experimentation has proved that if certain peculiar

PSM V46 D075 Watch escape wheel swiss lever and balance.jpg
Fig. 4.—Scape-wheel. Fig. 5.—Swiss Lever. Fig. 6.—Balance.

curves and inclinations are given to portions of the hairspring it will compel the balance to beat equal time for a longer or shorter swing. What these curves are the student learns from drawings which he follows as closely as he can, and then proceeds on the "cut and try" principle. Timing for heat and cold is a simpler matter, and is accomplished by adjusting the screws on the balance. Every respectable balance is made, by means of a combination of brass and steel hoops, to adjust itself more or less accurately in changes of temperature. But to bring about great accuracy in this respect requires much patience and experimentation. Then comes the adjustment for changing positions. If a watch runs a little faster lying down, the bearing affected by that