Crescograph

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).

[2] The electronic crescograph plant movement detector is capable of measurements as small as 1/1,000,000 of an inch.

The component which actually measures the movement is a differential transformer along with a movable core hinged between two points.

It can record plant growth, magnifying a small movement as much as 10,000,000 times.

This machine is highly sensitive; Bose padded the legs of the table on which the Crescograph is being used with India-rubber sponges.