^^6 Notices refpeSimg Nexv Books. 



the hofpital of incurables, after having interfered, to no pur- 

 pofe, in the epifcopal revokition. 



Never was aftrononier expofcd to fo many hardfliips in 

 making ohfervations. By the excelllve heat of Bagdad he 

 was rtQiiccd fouietinics to a rtate of the greateft debility, and 

 his laborious and dangerous journeys alwaVs brought on fevere 

 illnefs. He died a vititim to his zeal ; and itincreafes our re- 

 gret, that tlie number, of the martyrs to aCtronomy is already 

 fo great. [The annexed engraving reprefents Beauchamp iii 

 his Arabian drcfs.] 



LXI. Notices refpcSl'ing New Books. 



Ausfuhrliche Gefchichte der Theoretifch Praktifchen XJhrmc- 

 cherkunji, &c, A Hiftory of Clock- and Watch-making, 

 both Theoretical and Pra6tical, fince the earlieft Method 

 of dividing the Day to the End of the i8th Century. By 

 I. li. MoRiz PoPEE, 1801. 8vo. 564 pages. 



[Concluded from p. 276.] 



V\U. FURTHER progrefs of the theoretico-praElical part of 

 clock- and watch-making till the end of the iSth century. — In 

 order to render theofcillationsof the large clocks ifochronous, 

 Huyghens invented the cycloidal plate ; and De la Hire aflures 

 us, that this cycloidal pendulum clock, though often com- 

 pared with the motion of the fixed ftars, did not differ in 

 eight days but a few feconds from the mean motion of the 

 fun. But Huyghens himfelf foon found that the plate could 

 not be made in a cycloidal form, and that the filken threads 

 by which the pendulum vvas fnfpended did not anfwer the 

 purpofe, but that a pliable fpring could be ufcd in their flead. 

 He then invented, for the purpofe of more perfe^l regula- 

 tion, that fingular pendulum called pirouette, which has a 

 cruciform i^iotlon. This, however, was alfo rejcfted. About 

 the end of the 17th century, Derham and Hook conceived 

 the idea of making the pendulum fwing in fmall arches, and 

 applying heavy lenticular weights. This method was adopted 

 by Le Bon and Da Rivaz at Paris, and by Clement in Lon- 

 don, who alio invented the lo called Englifli pallet. The 

 author here gives aii account of the difcovery, that the 

 pendulum does not every where vibrate with the fame velo- 

 city, its vibrations being quicker near the pole and (lower 

 towards the equator; on which account, clocks that go well in 

 one place alter their rate of going when brought near to the 



pole 



