We guarantee that with a
detent and spring made as we show, there will be no tendency to cockle,
or if there is, it will be too feeble to even display itself. Those who
have had extended experience with chronometers cannot fail to have
noticed a gummy secretion which accumulates on the impulse and
discharging stones of a chronometer, although no oil is ever applied to
them. We imagine this coating is derived from the oil applied to the
pivots, which certainly evaporates, passes into vapor, or the remaining
oil could not become gummy. We would advise, when setting jewels (we
mean the locking, impulse and discharging jewels), to employ no more
shellac than is absolutely necessary, depending chiefly on metallic
contact for security.
DETAILS OF CONSTRUCTION.
We will now say a few words about the number of beats to the hour for a
box or marine chronometer to make to give the best results. Experience
shows that slow but most perfect construction has settled that 14,400,
or four vibrations of the balance to a second, as the proper number, the
weight of balance, including balance proper and movable weights, to be
about 51/2 pennyweights, and the compensating curb about 1-2/10" in
diameter.
Pages:
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282