1Q2 SOME ACCOUNT OP THE 



TJftuanah. They exactly rcfemble one another, and 

 are designed for the fame purpoie, which is to ob- 

 ferve the altitude and azimuth of the heavenly bodies, 

 they are two in number, on purpoie that two perlbns 

 may obferve at the fame time, and fo compare and 

 correct their obfervations. 



Thefe buildings are circular, and in the centre of 

 each is a pillar of the fame height with the building 

 itfelf, which is open at top. From this pillar, at thf 

 height of about three feet from the bottom, proceed 

 radii of ftone horizontally to the circular wall of the 

 building. Thefe radii are thirty in number ; the 

 {paces between them are equal to the radii themfelves, 

 which meafiife in breadth as they recede from the pil- 

 lar, fo that each radius and each intermediate fpace 

 forms a lector of fix degrees. 



The wall of the building at the fpaces between the 

 radii forms recedes internally, being thinner at thofe 

 places than where it joins the radii. In each of thefe 

 recefTes are two windows, one over the other ; and in 

 the (ides of the recefs are fcuare holes, at about the 

 inee of two feet, above cne another, by means of 

 which a perfon may climb to the top. On the edges 

 fe recciies are marked the degrees of the fun's 

 - rude, or rather the tangents of thole degrees fhewn 

 : lhach ' the centre pillar ; and numbered 



from the top, from one degree to forty-five. For the 

 altitude, when the fun fifes higher, the degrees arc 

 marked on the horizontal radii ; but they are num- 

 bered from the pillar outwards, beginning with one, 

 fo that the number' here pointed out by the fhadow, 

 the complement of the altitude. Thefe degrees are 

 fubdiyided into minutes. The fpaces on the wall, op- 

 pofite to 1 dii, are divided into iix equal parts, or 



degi lines drawn from top to bottom, but 



are net U led. By obferving on 



which 



