The wonders of modern mechanismA résumé of recent progress in mechanical, physical, and engineering science . The black part of the rim is made ofsteel, the lighter part of brass, and being firmly fastenedtogether a result is obtained that causes the balance tomaintain the same speed whether the temperature is hot orcold. As the usual vibration of a balance-wheel is at therate of eighteen thousand an hour, it can be seen that aslight expansion of the rim by heat would slow down thewatch materially, while exposure to cold would make it 28* 344 WONDERS OF MODERN MECHANISM. ruu fast
The wonders of modern mechanismA résumé of recent progress in mechanical, physical, and engineering science . The black part of the rim is made ofsteel, the lighter part of brass, and being firmly fastenedtogether a result is obtained that causes the balance tomaintain the same speed whether the temperature is hot orcold. As the usual vibration of a balance-wheel is at therate of eighteen thousand an hour, it can be seen that aslight expansion of the rim by heat would slow down thewatch materially, while exposure to cold would make it 28* 344 WONDERS OF MODERN MECHANISM. ruu fast. In the compensation balance, however, the brassexpands faster than the steel, and tends to make the rimcurl in with an increase of temperature, so that when it ishot the watch is inclined to run fast instead of slow, whichwould otherwise be the case. This tendency of the com-pensation balance to run fast when heated must be made toexactly balance the tendency which exists in the hair-springto slow down because of lost elasticity under heat. Whenthis is properly done we have a Avatch that will run accu-. THE COMPENSATION BALANCE. rately at all common temperatures. The small screws inthe balance-wheel may be set at any of the points numberedfrom 1 to 12, and by shifting them an adjustment of weightis obtained that causes the balance to throw in and out theexact weight required to alter the centrifugal force to meetthe requirements previously stated. If it is found that anincrease of twenty-five degrees in temperature causes thewatch to lose seven seconds an hour, screw No. 3 might bemoved to position No. 11, adding to the weight of the partof the rim that curled in with the heat, and causing the MACHINE-MADE WATCHES. 345 balance to travel faster, since the shifted weight wouldunder increase of temperature be nearer the centre, andexert less centrifugal force. Another device is provided to adjust the speed of thewatch when it is found to vary constantly in one is
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Keywords: ., bookcentury1800, booksubjectmachinery, booksubjectmechanicalengi
