Invented by John C. Briggs and patented in 1855. Many such clocks were made by the E. N. Welch Manufacturing Co. In the 1870s. The clock has a conical pendulum as the timekeeping element, a device first used by Robert Hooke in the 1660s for driving a telescope, although usually ascribed to the Dutch scientist Christiaan Huygens. Clocks using the conical pendulum have no escapement; the last wheel in the train carries an arm which rotates and turns the conical pendulum. Accuracy of timekeeping is less than with the conventional swinging pendulum because of the friction of the top support and the contact of the driving arm.