18 ÷ 3 = 6.0 = time of one interval.

_Résumé._

No. 1 6.0 seconds. 6.31 × 5 = 31.55
2 6.0 seconds. + 1.00
3 6.7 seconds. ----
4 6.3 seconds.
5 6.5 seconds. 32.55
6 6.7 seconds. 32.55 ÷ 6.31 = 5.159
7 6.0 seconds. With fork free 5.163
---- -----
Mean = 6.31 seconds Effect of scrape = - .044

_Specimen._

Circumstances as in first case, except that both forks were on their
resonators.

Coincidences were observed at--

21 seconds.
28 seconds.
36 seconds.
44 seconds.
51 seconds.
60 seconds.
60 - 21 = 39
39 ÷ 5 = 7.8 = time of one interval.