English: The first pendulum clock, invented by Dutch physicist Christiaan Huygens in 1657, and built by clockmaker Saloman Coster. This drawing is from Huygens' 1658 treatise on the clock, Horologium. The pendulum was driven by a verge escapement mechanism, so it had a very wide angle of swing compared to modern clocks, perhaps 80° to 90°. The clock was weight-driven, using an ingenious arrangement of two weights linked by a loop of cord. In order to "wind" the clock, the larger weight was simply lifted to the top. Alterations to image: removed caption.