"[Following Galileo...] The next great inventor and improver of the science of horology was Hooke. In the year 1658 he invented the balance-spring, an improvement of the first importance in the art of timekeeping. ...Immediately after the invention of the balance-spring by Hooke, it was found that as the watches to which the spring was adapted kept so much more accurate time than those formerly made, it became desirable to divide the hour into more minute portions, and so the motion work was invented and the minute-hand applied."