Originally, this term referred to a feature on
stopwatches, which indicated that the watch in question had multiple
second hands. These hands would travel together (one behind/beneath the other) initially; they could be stopped independently (the first click stopped one hand while the second continued to sweep). Hence, the stopwatch had a 'split second hand.' The first use of the term to indicate fractional seconds of time was, according to
Tag Heuer, in
1946.
The Rutger Hauer movie was awesome, though.
"I saw a rat. So I shot it."
"You shot my kitchen!"
"Missed the rat."
-Dick Durkin and Harley Stone