C 627 ] 
angle ZVB; the angle ZVB fubtraded from BVO 
leaves ZVO — to the angle of the orbit of Venus 
with the vertical, ZVO = LVN. Therefore in 
the right-angled triangle LNV, the angle LVN be- 
ing given, and the fide LV, the fide VN, = the par- 
allax of longitude, and the fide L N, = to the paral- 
lax of latitude, may be found. The parallax of lon- 
gitude is reduced to time by knowing the horary 
motion of Venus in her orbit or path. Thus the value 
of one fecond of longitude is known in time. But 
to reduce the parallax of latitude to time, in Fig. 2d. 
Let ECP reprefent the ecliptic, Or B the path of 
Venus over the Sun as feen from the center of the 
earth, LRf) the path of Venus as affeded by paral- 
lax a-t any one place, C r the neareft diftance of the 
centers of the Sun and Venus as feen from the cen- 
ter of the earth, C R the neareft diftance of the 
fame centers as feen from the place of obfervation, 
Rr or NV the parallax of latitude, CS the Sun’s 
femidiameter, VS the femidiameter of Venus, N r J 
the difference of the femichords rv and R V, C V 
and C v = the difference of the femidiameters of 
the Sun and Venus. 
In the right-angled triangles C rv and CRV, two 
fides are given, therefore the other fides rv and R V 
may be found the difference of thefe two fides Nt 
being reduced to time, by the horary motion of Ve- 
nus in her path, will give the time anfwering to the 
parallax of latitude. The parallax of longitude being 
added to or fubtraded from the Parallax of latitude, 
as the cafe requires, will give the retardation or acce- 
leration of the contad at the place of obfervation, 
after 
