crescograph

thumb|Crescograph, Bose Institute, Kolkata A crescograph is a device for measuring growth in plants. It was invented in the early 20th century by Jagadish Chandra Bose.

The Bose crescograph uses a series of clockwork gears and a smoked glass plate to record the movement of the tip of a plant (or its roots). It was able to record at magnifications of up to 10,000 times through the use of two different levers. One lever records at 100 times magnification while the other lever takes that image and records at another 100 times magnification. Marks are made on the plate at intervals of a few seconds, demonstrating how the rate of growth varies under varying stimuli. Bose experimented with temperature, chemicals, gases, and electricity.