ASTRONOMY. 55 



57, 58., then extracting the square root, and 

 rejecting the powers of the compression greater 

 than the first. 



See CAGNOLI Trigonometric, 1558. 



b. The tangent of the angle ACE (fig. 3.), which the 

 diameter answering to the latitude A, makes with 

 the greater axis of the meridian, or with the plane 



of the equator, is x tan A. CAGNOLI, 1339. 



c. The angle at the centre being thus found, the angle 

 which the semidiameter CE makes with the verti- 

 cal EG is also found, being the difference between 

 the former angle and the latitude of the place. 

 The angle which the diameter makes with the ver- 

 tical is greatest at 45, where it amounts to 11' 9" 

 when the compression is .00324. Base Metrique t 

 torn. in. p. 292. If the compression is greater, 

 this angle also becomes greater. 



d. The figure of the earth may not only be determi- 

 ned by comparing two degrees of the meridian 

 with one another, but it may also be found by com- 

 paring a degree of the meridian, with the degree 

 of a great circle perpendicular to the meridian, in 

 the same latitude. 



62. If we suppose the earth to be cut at any 

 point by a plane perpendicular to the meridian in 



that 



