14 ASTRONOMICAL AND 
dius, will be equal tone, the parallax in longitude. In. occul- 
tations, when the moon’s latitude is confiderable, this augmen- 
tation muft take place ; but in folar eclipfes, her latitude is al- 
ways fo fmall, that the difference between mr and ze is imper- 
ceptible ; therefore, mr may be confidered as the true mier 
in longitude. 
As the fides of the triangle yr are very fhort, it may be 
reckoned a plain one, without any perceptible error ; and the 
fides » 7 and mr may be found by plain right-angled trigonome- 
try, the hypotenufe Dm, and the angle 5» 7 = angle pp Z, 
being given. ^ 
For fide yz, the moon's parallax i in latitude. 
Radius : ) m in seconds" ` Sinë — mDr : : Bde di ag in 
feconds. Cees ra 
7 feconds. 
AW" ME op 
- GENERAL RULES FOR APPLYING THE PARALLAXES. 
Ina place in north latitude, when the moon's latitude fs 
north, if the parallax in latitude is lefs than the true latitude of : 
the moon, fubtraé it from her latitude ; the remainder will be 
. her vifible latitude north. If the nes be the greater, fub- 
tract her latitude therefrom ; the remainder will be the moon’s - 
vifible latitude fouth. If the true latitude of the moon be 
fouth, the parallax in latitude, whether greater or lefs, muft be - 
. added, and the vifible latitude will be fouth. Thefe rules muft 
_ be inverted, when the latitude of a place is fouth. 
The 
