This apparatus was designed to demonstrate a projectile experiment designed by Galileo (1564-1642). A ball runs down the curved slope at the top left and is projected from the end of the slope. It leaves the slope with a certain horizontal speed, which is maintained as it falls. However, it also accelerates, in the normal way for a falling object. The combination of a steady horizontal speed and an accelerating downward motion produces a curved parabolic path. The apparatus was made by George Adams of Fleet Street, instrument maker to the king.
© Science Museum / Science & Society Picture Library