Rules and Practice for Adjusting Watches

nal Errors and the I

lly because of frictional errors. It would therefore seem that if the watch was mec

ance to be made in equal time and that to attain this, the center of gravity of the spring must coincide wit

ction and fitted with an isochronal spring it would

in Practice and What I

four hour test in any position may prove that the long and short arcs are made in equal time showing the spring to be isochronous and yet the position variations have not been accounted for. In this connection experience proves that a spring showing a

e, because a spring showing a perfect isochronal rate has been altered for the purpose of counteracting some positio

ically isochronous, with the idea of making it act in opposition to the position error and the

be caused by dirt and gummy oil, damaged pivots, or balances that are out of poise. The watch should be in first-class conditio

the entire twenty-four hours running. It is immaterial as to whether the r

ain and a loss in the rate, even though the time

watches for twenty-four hours in any one of the vertical positions and noting the variation in periods of from four to twelve hours and by comparing the variation in t

of Extreme Isoc

keeping, may be found in the factor of, out of poise and uneven motive force, which is one of the elementary principles of adjusting. This feature should be thoroughl

then drops to one and one-quarter turn and finally to one turn or less during the latter part of the twenty-four hours, the poise error will have considerable effect. This factor is not perceptible in the flat positions, but shows up to the full extent in the vertical positions and the

l be reversed and the watch will gain when the motion is over one a

e error and experiments will prove that serious isochronal variations can be traced to the

ntain this motion for twenty-four hours, therefore the poise must be as nearly perfect as possible. The nearest approach to even motion of

been adopted by at least two of the American manufacturers of fine watches during the past few years with considerable benefit in producing even motion and the use of lighter mainsprings.