758 Mr. button’s Calculations to afceriain ' 
deducing the latter from the former fhall be explained 
after we have, as below, regiftered the altitudes of all the 
pillars as they were computed. This regifter confifts of 
fixteen tables, namely four quadrants of lpaces in the al- 
titudes, and four in the depreflions, for each oblervatory, 
as fpecified in the titles of them. The numbers are feet, 
like all the other dimenfions. The numbers on the fame 
horizontal line from left to right are fuch as are all in the 
lame ring; and thofe in one and the fame vertical co- 
lumn are in the fame fedlor, or between the fame two 
radii; the number of the ring, counted from the com- 
mon center, is written in the left-hand margin; and the 
number of the vertical column or diftance of the fpace 
or fector from the meridian, at the top; alfo the radius of 
each ring, that is, the line from the common center to 
the middle of the ring is written on the fame line with 
it, in the right-hand margin. It may be further re- 
marked, that in fuch little fpaces as were cut through by 
the boundary line between elevations and depreflions, 
thereby making but a part of fuch fpaces in each of 
thofe denominations, each fpace was accounted as a whole 
one; but then the mean altitude of depreflion in each 
part was diminifhed in the proportion of the whole fpace 
to the part of it fo included in the boundary. The alti- 
titudes and depreflions are put down firft with refpect to 
2. the 
