On the Origin of Clockwork, Perpetual Motion Devices, and the Compass

Transcriber's note: The original three column Chronological Table has been replaced by a single column table with the same chronological order to make its reading easier at all browser settings.
Contributions from The Museum of History and Technology: Paper 6
On the Origin of Clockwork, Perpetual Motion Devices, and the Compass Derek J. de Solla Price
In each successive age this construction, having become lost, is, by the Sun's favour, again revealed to some one or other at his pleasure. ( Sūrya Siddhānta , ed. Burgess, xiii, 18-19.)
HE histories of the mechanical clock and the magnetic compass must be accounted amongst the most tortured of all our efforts to understand the origins of man's important inventions. Ignorance has too often been replaced by conjecture, and conjecture by misquotation and the false authority of common knowledge engendered by the repetition of legendary histories from one generation of textbooks to the next. In what follows, I can only hope that the adding of a strong new trail and the eradication of several false and weaker ones will lead us nearer to a balanced and integrated understanding of medieval invention and the intercultural transmission of ideas.
Furthermore, even if one admits the use of clocklike gearing before the existence of the clock, it is still necessary to look for the independent inventions of the weight-drive and of the mechanical escapement. The first of these may seem comparatively trivial; anyone familiar with the raising of heavy loads by means of ropes and pulley could surely recognize the possibility of using such an arrangement in reverse as a source of steady power. Nevertheless, the use of this device is not recorded before its association with hydraulic and perpetual motion machines in the manuscripts of Riḍwān, ca. 1200, and its use in a clock using such a perpetual motion wheel (mercury filled) as a clock escapement, in the astronomical codices of Alfonso the Wise, King of Castile, ca. 1272.