INFLUENCE OF SUSPENSION ON WATCH, 375 



the suspension we may use stout silk threads 

 attached to the pivots of a marine chronometer 

 taken out of its gimbals, or attached to a pocket- 

 watch, at opposite points of its circumference, 

 by any convenient sling or by means of a cord 

 knotted round the watch like a parcel. The 

 suspending threads may be one, two, or three feet 

 long, and the upper ends may be attached to 

 adjustable points of support on a fixed horizontal 

 bar. We readily thus find that we can make it 

 go either fast or slow as we choose, by shifting 

 the points of support nearer to or farther from 

 the centre. When the points of support are 

 very near, the time of vibration of the chrono- 

 meter as a whole if turned a little round its 

 vertical axis from the position in which it hangs 

 in equilibrium and let go, is much longer than 

 that of the balance-wheel. If the watch-case is 

 now steadied and left to itself, with the watch 

 going, the reaction of the balance-wheel, through 

 the spring, against the frame, gives rise to a 

 vibration, illustrated by Fig. 2, in which the 

 balance-wheel and the rest of the chronometer 



