German watch and watch movement, 16th century

Early German watch and watch movement, 16th century.
The watch movement shown on the left dates from the first half of the 16th century and is made mainly of steel. Because the balance has no spring it does not have a natural frequency of vibration and the timekeeping depends on the driving force. With the primitive mainsprings used to drive these watches this force rapidly decreases as the spring unwinds. To overcome this defect the movement is fitted with a stackfreed, a primitive device which attempts to even out the force produced by the spring. The rate of the watch is altered by means of a hog's bristle which limits the arc through which the balance can swing: the smaller the arc the faster the watch will go. The watch on the right is later, dating from the end of the 16th century. Its movement is similar to the one on the left except that its plates and some its wheels are made of brass.
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Measuring Time
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