|historische (astronomische) Zeitmesser|
Interval timer, by William Hardy, London, about 1825
high-precision instrument was used in the Royal Observatory for accurately measuring
short intervals of time, such as successive transits of stars, across the meridian.
The timer starts when the button on the side of the case is held down and stops
immediately it is released."
|Quelle: "Royal Greenwich Observatory ": http://www.rog.nmm.ac.uk/museum/RGO/objects5.html|