Seiko M-6 Instructions Manual page 83

● The accuracy of mechanical watches is indicated by the "daily rate."
● The accuracy of mechanical watches may not fall within the specifi ed
range of time accuracy because loss/gain changes due to the position
of the watch, which is dependent on the conditions of use, such as
the length of time during which the watch is worn on the wrist, arm
movement, and whether the mainspring is wound up fully or not, etc.
● The loss/gain of mechanical watches is not measured by a daily
rate, but by daily rates of one week or so.
●Accuracy variation according to temperature
・ The parts that compose the accuracy of mechanical watches are made
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of metals. It is well known that metals expand or contract depending
on temperatures due to metal properties. This exerts an eff ect on the
accuracy of the watches. Mechanical watches tend to lose time at high
temperatures while they tend to gain time at low temperatures.
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Accuracy of Mechanical Watches