94 ESSAYS AND OBSERVATIONS 



true place Is at the correfpondent point of 

 the furface of the earth j , confequently, 

 the vif. Ion. and lat. 2) a 0, vg^, 'vf, 

 muft be increafed in the ratio of the di- 

 ilance of the point 'V from the fpedator's place 

 on the furface, to its diftance from the point V 

 on the diflc But, as the horizontal femidiame-. 

 terof the moon fliould likewife be increafed 

 in the fame ratio, it will equally anfwer the 

 purpofe of finding the times and phafis of an 

 eclipfe, to let thefe continue unaltered, and to 

 diminifh the fun's apparent femidiam&ter in 

 the fame ratio. 



7. Let C P be the axis of the earth pro- 

 jefted on the difk, F M D the ellipfe into 

 which the parallel of the given place is pro- 

 jeded, D F its greater axis, O M its leffer fe- 

 miaxis, V G perpendicular to C O 3 M H, 

 G K, perpendiculars to C V/, and M I, G L, 

 at right angles to C N j and, for fhort^ning 

 the rules, put CW, the femidiameter of the 

 difk, or the horizontal parallel D a Q, equal 

 to the radius of the tables of fines and tan- 

 gents. 



8. For computing the parallaxes.', V Ay 

 V B, it will be convenient firfl to fuppofe the 

 fun in the meridian, and the place of the ver- 

 tex 



