D. J. Macgowan on Chinese Horology. 243 
before our era. ‘The forms of the apparatus have been various, 
but they generally. consisted of an upper and a lower vessel, 
always of copper, the former having an aperture in the bottom, 
through which water percolated into the latter, where floated an 
index, the gradual rise of which indicated successive periods of 
time. In some, this was reversed, the float being made to mark 
ume by its fall. A portable one was occasionally employed in 
ancient times on horseback, in military tactics. 
Instruments constructed on the same principles with the above 
were in use among the Chaldeans and Egyptians at an early 
period; that of Clesbius of Alexandria being an improvement 
over those of more ancient times. The invention of Western 
Asia, was doubtless wholly independent of that of the East, both 
being the result of similar wants. Clepsydras were subsequently | 
formed of a succession of vessels communicating by tubes pass- 
ing through birds, dragons, &c., which were rendered still more 
ornamental, by the indices being held in the hands of genii. 
The earliest application of motion, to the clepsydra, appears to 
have been in the reign of Shuen-ti(126—145 A. D.) by Tsiang- 
hung, who constructed a sort of orrery; representing the apparent 
Motion of the heavenly bodies around the earth, which was kept 
in motion by dropping water.> There is reference also to an in- 
iustrumént of this description in the third century. — 
In the sixth century an instrument was in use which indicated 
the course of time by the weight of ‘water as it gradually came 
from the beak of a bird and was received ona vessel in a balance, 
every pound representing a kik. About this time, mercury began 
to be employed instead of water, which rendered the aid of heat 
IN Winter unnecessary. Changes were. made also in the relative 
humber of kik for day and night, so as to vary with the seasons. 
_ As in Europe, monks of the Roman church devoted consid- 
erable attention to mechanical inventions, especially in the con- 
and sunk eve hour, requiring of course frequent attention. 
. Although their knowledge of hydrodynamics has ever been very 
J . paler 
limited, the Chinese appear to have been the first to devise that 
pin = clepsydra to which the term water-clock is alone properly 
Pphed, that is to say, composed of apparatus which rendere 
Watching unnecessary by striking the hours. Until the com- 
mencement > eighth he per: employed to watch 
mt: 
may : 
