Hipp chronoscope, Swis, 1888.
© Science Museum / Science & Society Picture Library
Invented by Matthias Hipp of Neuchatel, Switzerland, this device was used to measure short intervals of time to an accuracy of 1/1000th of a second. Its timekeeping element is not a pendulum but a metal reed which vibrates 1000 times per second above an escape wheel; one tooth of the escape wheel pases it every one-thousandth of a second. Hipp's chronoscopes were originally used in military research experiments to measure the speed of projectiles, but achieved popularity with the advent of experimental psychology laboratories in the late 19th century, in which they were used to try to determine the speed of thought.