On Sun, 19 Apr 2015 23:25:10 -0400, Chuck Harris wrote: >1/5th second is simply the rate at which the balance >wheel on a standard stopwatch ticks... 18000BPM. >-Chuck Harris You must mean 18000BPH. There are many balance wheel rates in use from 4.5BPS to 10BPS and higher. My Elgin "jitterbug" stopwatch runs at 40BPS. Bill Beam NL7F