396 TIME-KEEPING IN GREECE AND ROME. 



But improvements in the clepsydra such as have been described, not- 

 withstanding the ingenuity and mechanical skill they displayed, are of 

 little consequence to us, since they were not towards the accomplish- 

 ment of the final result but away from it. The actual steps towards 

 the modern clock appear to be these : First, the employment of the or- 

 dinary rack and pinion device. If we are right in attributing the in- 

 vention of gear-wheels to Archimedes, this application could not have 

 been made earlier than the middle of the third century b. c. (287 to 

 212). It is attributed to Ctesibius, who, for many reasons as I have 

 said already, is placed a century later than this. A series of teeth, 

 commonly called a rack, was attached to the side of the rod, which was 

 supported by the float, and had heretofore served only as an index. 

 Fixed on a horizontal shaft above the vessel was a small toothed wheel, 

 with which the toothed rack engaged, and which was, therefore, caused 

 to turn by the rise of the float. On this shaft was a pointer attached 

 like the hour-hand of a clock and travelling over a similar dial. To make 

 this hand complete a circuit in twelve or twenty-four hours, is obviously 

 only a question of the proportion of parts. The next step forward dis- 

 pensed with the rack and pinion, and reallj^ was in the line of greater 

 simplicity. In place of the toothed wheel a grooved puUy was used, 

 over which passed a cord from the float, being kept tight by a weight 

 at the other end. The hand remained on the wheel shaft as before, and 

 with the gradual rise of the float, traversed the dial. 



We have reached the point where we may say '■^presto, change,^'' and 

 behold, a clock springs into view, for it is instantly apparent that with 

 this structure it is no longer the water that advances the hand ; water 

 is not the motor now. The weight is the motor, and its fall is retarded 

 by the float, which ouly j)ermits its descent as fast as the rise of water 

 in the vessel permits its own rise. We have an actual weight clock, 

 with what we must be content to regard as a water escapement; it is 

 far enougli from our perfected time-piece, but in respect to its essential 

 elements it differs in but one, and henceforth the problem of the clock 

 is only that of escapements. But we need not expect it to be solved at 

 once. It will be centuries before the actual x)roblem will be recognized, 

 so great is the obscurity with which the Roman time system has be- 

 clouded the subject. 



There is a long and mournful perspective before us. The golden age 

 of Roman literature is here, but she has yet to see the greatest extent 

 of her empire and the summit of her own magnificence. Along line of 

 Coesars will come, base and noble alternating, fler decline will follow 

 her glory ; her palaces are to be plundered by barbarous northern in- 

 vaders; her empire is to be shattered; out of her vast domain new 

 peoples and nations and empires scarcely less mighty than her own are 

 to spring, while she herself sinks to the paltry dimensions of a village. 

 Her polished speech shall die from men's lips, but the rude dialects of 

 her provinces, mingling with the uncouth tongues of illiterate Franks 



