[time-nuts] Visual clock comparison

Jim Lux jimlux at earthlink.net
Sun Apr 19 12:58:04 EDT 2015

On 4/18/15 7:02 AM, Bob Camp wrote:
> Hi
> Many years ago while standing around (between races) with some pretty good stopwatches, a group of us decided to see
> just how well a set of people could time the same pair of start / stop events. Our conclusion was that as a
> group we could get agreement to +/- 1/5 second pretty consistently once we practiced a bit.
> The obv

Hence the reason that horse races are traditionally timed in 1/5th 
second increments.  (1/5th second is also about 1 stride for a race 
horse at full gallop 3.5-4 m/stride... 17 m/s)

a bit of googling turns up


"Stopwatches timing to 1/5 second were being used to time races befor 
1731, by which time they were in commercial production, seven years 
befor ethe earliest use of 'stop-watch' known to the OED"

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