[ 2 7 * ] 
prefcribed to be ufed when the altitudes are under I o 
degrees. 
i ft. Making ufe of the apparent altitudes of the 
Moon and ftar uncorreded, compute arches the firft 
and fecond by the directions contained in the rule of 
refradion. 
2dly. Taking arch the fecond for arch A in the 
rule of parallax, compute the effed of parallax ac- 
cording to rule the fecond. 
3 dly. With arches the firft and fecond compute the 
effeCt of refraction by rule the firft. 
4thly, and laftly. Applying the two corrections of 
parallax and refradion duly, according to the rules, to 
the obferved diftance of the Moon from the ftar, you 
will have the true and corred diftance of the Moon 
from the ftar, cleared both of refradion and paral- 
lax. 
A RULE 
For computing a fecond, but fmaller corredion than 
the firft, neceffary to be applied to the obfervations 
of the diftance of the Moon from a ftar on ac- 
count of parallax. 
Call the principal effed of parallax, found by the 
preceding rule, the parallax in diftance ; and find 
the parallax anfwering to the Moon’s altitude. Then 
to the conftant logarithm 0.941 add the logarithm 
of the fum of the parallax in altitude and the paral- 
lax in diftance, the logarithm of the difference of 
the fame parallaxes, and the cotangent of the ob- 
ferved diftance of the Moon from the ftar (correct- 
ed for refradion, and the principal effed of paral- 
lax), the fum, abating 13 from the index, is the 
logarithm 
