_Résumé._

1 5.9
2 6.2
3 6.2
4 6.2
----
Mean = 6.13 = time of one interval between coincidences.

In this time the watch makes 6.13×5 = 30.65 beats, and the forks make
30.65 + 1 = 31.65 beats.

Hence the number of beats per second is 31.65 ÷ 6.13 = 5.163.


_Specimen._

Circumstances the same as in last case, except that standard Vt₃ fork was
allowed to trace its record on the lampblacked paper, as in finding its
rate of vibration.

Coincidences were marked at--

59 seconds.
04 seconds.
10.5 seconds.
17 seconds.

77 - 59 = 18.