Telemotor. Steering-gear which controls a steering engine by hydraulic pressures set up by movements of the steering-wheel.
Telescope. Optical instrument for magnifying image of distant objects, so making them to appear nearer. Crude form was in use before 1570. In 1608, two Dutch spectacle makers, Jansen and Lippershey, made three instruments 'for seeing at a distance'. Galileo improved on these by using double concave eyepieces. Kepler introduced convex eyepiece. Light-collecting power depends entirely on area of object glass. Different types include terrestrial, refracting, reflecting, and prismatic telescopes-and the periscope.