ASTRONOMICAL LABOURS OF JAYASINIIA. 193 



which of thele the fhadow of the pillar falls, we may 

 determine the fun's azimuth. The parts on the pillar 

 oppoiite to the radii, and the intermediate fpaces, in all 

 iixty, are marked by lines reaching to the top, and 

 painted of different colours. 



In the fame manner that we determine the altitude 

 and azimuth of the fun, we may alio obferve thole oi 

 the moon, when her light is ftrong enough to caft a 

 fhadow. Thole of the moon at other times, or of a 

 ftac, may alfo be found by placing the eye cither on 

 one of the radii, or at the edge of one of the receiies in 

 the wall (according as the altitude is greater or 

 than forty-five degrees,) and moving along till the 

 top of the pillar is in a line with the object. The de- 

 gree at which the eye is placed will give the altitude, 

 or its complement, and the azimuth is known from 

 the number of the radius to which the eye is applied. 



The dimenlions of the building are as follow : 



Length of the radius from the circumfe- Ft. In. 

 rence of the centre pillar to the wall ; 

 being equal to the height of the wall 

 above the radii -*--_--- 24 (If 



Length of one degree on the circular wall 5' 



Which gives for the whole circumference l/'2 6 

 Circumference ^ meafured by a handkerchief t .>. OT 

 of the pillar > carried round it s ' * 



f Deduced from its coloured"! 

 < divifions meafured with > iy 2* 

 ^ compalles - - - J 



I do not fee how obfervations can be made when 

 the fhadow falls on the fpaces between the ftone radii 

 or fectors ; and from reflecting on this, I am inclined 

 to think, that the two inftruments, inftcad of being 

 duplicates, may be luppkmentary one to the other*; 



the 



