rilOCEEDIXGS OF TUE P OLYTECIIXIC AsSOCIATIOX. 1041 



the meclianisiii was concealed. Tliis column turned on its axis 

 in one vear, and liad the hours marked by circles, varyino;, to 

 show tlie long and short days, and nights, or winter and summer. 

 Beside this culnnin stood the Mgures of two boys, one of wlioiu was 

 re])resented as crying- heartily, v\'hile the tears fell into a basin, ran 

 across the pedestal in a concealed way, and into a large vertical tul)e, 

 witli its bottom closed. The other boy stood on the cap of a rod, 

 attached to a float resting on the water in this tulje, and consequently 

 rose as the water came in, to the right of the column in twenty-four 

 hours. When it "arriv^ed at the top a syphon came into })l'<!y, and the 

 whole contents of the tuljo was dischai'ged into a bucket of an over- 

 shot water wheel. This wheel had six buckets only, and thus per- 

 formed a revolution in six days. On its axis was a pinion of six 

 leaves driving a wheel of sixty teeth attached to a vertical shaft, and 

 this in turn had a pinion of ten, driving a wdieel of sixty-one teeth on 

 a shaft attached to the colunni, and thus the column was turned fully 

 round in 366 days. In this we find carving, turning, founding, an 

 overshot water wheel, the art of transmitting motion and changing 

 its direction by means of toothed wheels, and the porportioning of 

 nundiers of wheels and pinions, and the application of the syphon. 

 The eye of the weeping boy was fitted with a pierced jewel to pre- 

 vent its enlargement and fouling. 



Vitruvius makes mention of a clepsydra which told the hours, 

 the moon's age, the zodiacal signs, &c. The principle was that of a 

 float and to^')thed column, which, as it rose, drove toothed wheels, and 

 these in turn imp)elled others, and figures were made to move, obe- 

 lisks to turn, pebbles to be discharged, trumpets to sound, and many 

 otlier tricks. The aperture for admission of water in this was a per- 

 forated gem. 



The so called Temple of the Winds, at Athens, was a clepsydra on 

 an immense scale, and Vvas the timedvceper of the day. It was sup- 

 posed to have been built by Androndicus Cyrrhestes, and it derives 

 its name from the figures of the eight winds cut in I'clief on its walls, 

 with their names on the frieze above them. Both Varro and \'itru- 

 vius call this a horologium, from its containing an immense water 

 clock, which was supplied from a spring under the cave of Pan, on 

 the northwest of the Acropolis. I can find no description of its 

 mechanical details, and it is in such a state of ruin at this day that 

 nothing definite can be arrived at. W\ that remains is a portion of 

 ,the stone aqueduct in which the water was brought. These writers 



[Inst.] 66 



