386 TIME-KEEPING IN GREECE AND ROME. 



unchanged for a long period, we hazard little in assuming that they 

 date from a remote epoch. A description of the Hindoo instrameut 

 appears in a Sanscrit work on astronomy in which it is adopted for 

 astropomical observations, and Chinese writers do not hesitate to 

 ascribe the invention to Hwang-ti, who floarished, according to their 

 chronology, more than twenty five centuries before our era, and its 

 later improvement by the introduction of the float to Duke Chau, 

 fourteen centuries later. 



In describing these three devices in the order in which I have placed 

 them I do not mean to be understood as intimating that they have 

 followed the same order in respect to the time of their development 

 nor that they have been transmitted from one people to another in the 

 same order. I have, for convenience, proceeded from the lowest form 

 to the highest; but it may well be true that the lower was an adapta- 

 tion from the higher, fitting it for coarser needs, and so being in a 

 certain sense an improvement. Consideration of the lines of commerce 

 might in fact lead to the suspicion that the Malay got his notions 

 from the Chinese, since they must for many centuries have sailed the 

 same waters and been in frequent contact. 



But we may come further west. Writers on this subject, while 

 attributing to the Chaldeans the invention of the sun dial, do not 

 generally accredit them with the knowledge of any other instrument 

 for measuring time. But if we may take as an authority Sextus Em- 

 piricus, who wrote near the end of the second century of our era, 

 they had, as he tells quite minutely, the same device, and used it in 

 their astronomical observations. "They divided," says this author, 

 "the zodiac into twelve equal parts, as they supposed, by allowing 

 water to run out of a small orifice during the whole revolution of a 

 star, and dividing the fluid into twelve equal parts, the time answer- 

 ing for each part being taken for that of the passage of a sign over 

 the horizon." I see no reason for doubting this. In fact the division 

 of the zodiac into twelve signs seems to require a means of measuring 

 the passage of time at night, and this fact and the story just quoted 

 tally with the conclusion that an instrument of the common generic 

 character borne by all the forms I have described was known among 

 widely distinct peoples of Asia before the dawn of European civiliza- 

 tion. 



Such an invention is not likely to be lost by political changes while 

 supremacy in the exact sciences is maintained. We know that down 

 to the Medo-Persian conquerors of Babylon each successive dominant 

 race adopted, as has often happened in history, the dress, the manners, 

 and the arts of the conquered; and we need not doubt that this instru- 

 ment was in use in the Persian Empire when its sword first crossed 

 that of the Greeks. 



No record exists of the introduction of the clepsydra into Greece. 

 We might infer from the absence of all reference to it by Herodotus 



