Mabch 22, 1907] 



SCIENCE 



445 



the top of the cylindrical vessel BCDF, 

 which gradually fiUs, the cork D, with its 

 attached pillar C, rising at the same time. 

 On the top of this pillar is an image hold- 

 ing an index which points to the divisions 

 on the large column above. Now when the 

 water rises in the cylindrical vessel it also 

 rises in the small tube FB, which consti- 

 tutes one leg of a syphon; consequently, 

 when the small tube fills and the index has 

 mounted to the top of the large column, the 

 water flows over the bent part B of the 

 syphon and the vessel is emptied into one 

 of the six troughs of the waterwheel K, 

 which is thus turned one sixth of a revolu- 

 tion, and the column, by means of the gear- 

 ing shown in the figure, 1/365 of a revolu- 

 tion, during which time the image falls 

 with its index to the bottom of the column, 

 to be ready for the next day. There are 

 ruled around the large column twenty-five 

 lines properly sloped with respect to each 

 other, so that the index may indicate the 

 hour on any day of the year. 



For the next fifteen centuries or more 

 after the introduction of this clepsydra of 

 Ctesibius, sundials and clepsydras were the 

 timekeepers of mankind. These were then 

 gradually supplanted by weight clocks. 



I am not able to give the date of the 

 manufacture of the first clock composed of 

 an assemblage of wheels actuated by a sus- 

 pended gravitating body and controlled by 

 a regulator of some determined shape and 

 dimensions, i. e., a regulated machine for 

 measuring time without the assistance of 

 water. 



There may be seen at the South Kensing- 

 ton Museum an old clock movement, now 

 controlled by a pendulum, which was re- 

 moved about seventy years ago from a 

 clock in "Wells Cathedral and which is said 

 to have been built by Peter Lightfoot, 

 about 1335, for the church of Glastonbury 

 Abbey, from which it was removed to "Wells 

 Cathedral in the reign of Henry "VIII., 



where, I believe, the dial and its accessories 

 may now be seen. In addition to indi- 

 cating the time, this clock was intended to 

 indicate the age of the moon and to show 

 its phase. Also it caused a man to strike 

 the quarter hours with his feet on two little 

 bells, and the hours on another bell before 

 him with a battle-axe that is in his hand. 

 It also set in motion four equestrian knights 

 equipped for a tournament. If the date 

 given for the clock is correct the figures 

 operated in connection with it are hardly 

 the original ones. One of the knights is 

 painted in the civil costume of the seven- 

 teenth century. 



About 1360 there was erected in the 

 tower of the palace of Charles V. of France 

 a clock constructed by Henry de Vick, of 

 "Wiirtemberg. This clock was made for the 

 simple purpose of telling the time of day 

 and was not expected to perform the nu- 

 merous feats that were so frequently re- 

 quired of clocks in earlier days, and may 

 be taken as a type of the earliest clock 

 movements. 



Front view. Side view. 



Fig. 3. Ancient Clock by Henry de Vick. 



From Fig. 3, giving both a front and a 

 side view, the operation of the clock may 

 be clearly understood. The motion of the 

 falling weight A is transmitted by means 

 of the wheels G, e, H and g to the wheel I; 

 this last wheel, by giving the pallets or 

 short levers, h, i, each a push alternately 

 by two teeth, at opposite sides of its cir- 



