80 Mechanical Philosophy. [Chap. 1. 



mical improvements of the last age, the formation 

 of many Tables^ exhibiting the places and motions 

 of the heavenly bodies. Among these are the 

 Cometarial Tables of Dr. Halley, since enlarged 

 and corrected by many hands, and particularly by 

 a number of eminent French astronomers. To the 

 same list also belong Tables of the Sun and Moo7iy 

 by le Monier, and de la Hire; the Sola?' Tables 

 of de la Caille, Dawes, de Lambre, and von Zach -, 

 and the successively improved Lima?' Tables of 

 Clairault, Euler, Mayer, Mason, and fmally, of 

 Burckhardt, founded on the observations of Burg 

 and Bouvard. Tables of all the primary PlanetSy 

 and their Secondaries, have been completed during 

 the period in question; among the most valuable 

 of which are those of Bradley, Cassini, de Lambre, 

 Wargentin, Vidal, Oriani, Schubert, Burckhardt, 

 and de Lalande. Tables of Parallax and Refrac- 

 tion have been formed by Bradley, Dimthorne, 

 and Shepherd, particularly the last, whose work is 

 a wonderful miOnmnent of industry and perseve- 

 rance. To these might be added a multitude of 

 others, published by individuals, and learned socie- 

 ties, various sets of which may be found in modem 

 books of astronomy. Those printed in de La- 

 lande's great systematic work, are probably ex- 

 ceeded by none extant in fulness and accuracy. 

 By means of these Tables, many complex calcula- 

 tions, which, without their aid, would cost the 

 labour of several hours, or even days, may now be 

 performed in an eighth or tenth part of the time 

 M'hich thoy formerly employed, and with much 

 greater assurance of a true result. 



Previous to the eighteenth century, though 



