130 TRANSACTIONS OF THE CANADIAN INSTITUTE. [VoL. II, 



impossibility of observing the time by the sun or stars during cloudy 

 weather. The first mechanical means employed was the flow of water, 

 drop by drop. Mechanisms of this kind named by the Greeks clep- 

 sydras, were of various forms ; in one class the flow of water was 

 weighed, in another the volume was measured. The clepsydra was 

 introduced into Egypt at the time of the Ptolemies ; from thence it 

 found its way to Greece and Rome. 



In these mechanical movements, and in others which followed in later 

 years, it became necessary to introduce complicated contrivances to mark 

 the variable length of the hours as the seasons advanced. Such is the 

 invincible power of habit that it exacted a continual change in the 

 movement of time-keepers in order to secure a notation of the unequal 

 hours. To denote these ever-varying intervals by machines of regular 

 motion, demanded all the inventive powers and skill, which the per- 

 tinacity of human ingenuity could call forth, to meet this requirement. 

 It will readily be understood that the ancient water clock was a great 

 and cumbrous contrivance, possessed only by royal personages, or 

 men of large wealth, and was regarded by the people of that age as 

 a product of much intellectual culture, and an evidence of the advance 

 of civilization. 



In the cloisters, the monks contrived to denote the passage of time by 

 the consumption of oil in lamps graduated for the purpose ; elsewhere by 

 the burning of candles, upon the wicks of which were placed a series of 

 knots at calculated intervals to mark periodic duration. In course of 

 years sand glasses were introduced, some of which were regulated to be 

 reversed at the end of each half-hour ; in which case it was indispens- 

 able to have watchers continually in attendance to turn them forty- 

 eight times during the twenty-four hours. 



The great defect of all these contrivances was, they had no principle 

 of continuity, and incessant watchfulness had to be observed. An effort 

 was therefore made to supersede the dropping of water, the consumption 

 of oil, the running of sand, and the burning of tapers, by having recourse 

 to suspended weights, and the introduction of wheelwork which should 

 move with regularity, and chronicle the hour. In 1288, one of these 

 machines was installed at Westminster Hall, which drew forth the 

 admiration of the people of London. Half a century later a similar 

 mechanical combination was erected at Dover Castle ; about this date 

 wheelwork clocks were placed in the Church of St. Gothard, at Padua, 

 and at different points in Europe. 



In every one of these complicated mechanical contrivances the exi- 

 gencies of " use and wont " had to be taken into account. Public opinion 



