1890-91.} REFORMS IN TIME RECKONING. 131 



of those dates would not countenance the adoption of hours of uniform 

 length throughout the year. It was exacted that hours of the day and 

 night should remain distinct, and should vary with the change of seasons. 

 So late as the fifteenth century this strange usage of counting the 

 passage of time by hours of unequal length remained in force. Gradu- 

 ally its absurdity became apparent, and the practice was introduced of 

 allowing the clocks to continue their movements at the same rate 

 night and day, commencing the reckoning as before at sunset. 



Although the hours were no longer required to be variable in length, 

 the commencement of the day at sunset continually varied with the sea- 

 sons. The necessity therefore remained of moving the hands of the 

 clock forward or backward nearly every day, or as it frequently happened 

 the assumed error was allowed to accumulate until it reached a quarter 

 of an hour. The total error in the latitude of Greenwich in any half 

 year was about four hours and a half; an error which was reversed 

 each half year, as the seasons changed. The same practice prevailed 

 generally throughout Europe, and the total discrepancy was greater 

 or less than four and a half hours according to latitude. 



This continual adaptation of the hands on the dial was known as " the 

 leap of the clock" {sauter rheure), and however perfect the mechanical 

 arrangements, it was in vain, under such a system, to look for precision 

 or uniformity of reckoning. 



The incessant interference, the daily application of thumb rule to move 

 the hands sometimes forward, at other times backward, an operation 

 termed " regulating the clock by the sun," to meet the daily changing 

 period of sunset, required so much attention that the ingenuity of skilled 

 men was directed to obtain some means of effecting the changes auto- 

 matically. M. Houzeau, in a lecture before the Royal Belgium Geogra- 

 phical Society, March, 1888, remarks on this point : — "Never was human 

 ingenuity expended upon any subject so irrational and of such little 

 merit. But habit which had lasted for centuries was at stake, and habits 

 never reason, the}' exact." Towards the end of the last century these 

 wonderful machines with automatical complications for pushing forward 

 or retarding the hours were objects of admiration in most of the capitals 

 of Europe, and so late as 1806 an honorary distinction was conferred by 

 the French Emperor Napoleon I., on the inventor and maker of a clock 

 possessing the proper increment needed to change with accuracy the 

 hands on the dial every day at all seasons. 



Some years before this date, the question was being asked, what 

 advantage results from having a daily change in the initial point 

 of the hours, why not have uniformity, summer and winter, as well as 



