V E S 



VENUS. See Planets, elements of. 

 VENUS, transit of. See Transit. 

 VENUS, phases of.( Vince. ) 



In the case of Mercury, Venus, and Mars, if = exterior / of elonga* 

 tion, i. e. supplement of the /, which the earth and sun subtend at the 

 planet, the visible enlightened part '. the whole disc I '. ver. sin. 6 : di- 

 ^ameter. 



Hence Mercury and Venus will have the same phases, from their in- 

 ferior to their superior conjunction, as the moon has from the new to 

 the full ; and the same from the superior to the inferior conjunction, as 

 the moon has from the full to the new. Mars will appear gibbous in 

 quadratures, as the / 9 will then differ considerably from two right B j 

 and consequently the versed sine from the diameter. For Jupiter, Sa- 

 turn, and the Georgian, the / never differs enough from two right /s 

 to make them appear gibbous, so that they always appear to shine with 

 a full face. In the case of the moon, the / 9 very nearly equals the / 

 of elongation ; .". the visible enlightened part of the moon varies very 

 nearly as the ver. sin. of its elongation. 



Venus is brightest between its inferior conjunction and its greatest 

 elongation; and its elongation at that time from the sun = 39. 44'. 

 Also at that time the visible enlightened part '. whole disc :: 0,53 : 2. 

 Venus therefore appears a little more than one-fourth illuminated, and 

 answers to the appearance of the moon when five days old. This situ- 

 ation happens about 36 days before and after its inferior conjunction. 



Mercury is brightest between its greatest elongation and superior 

 conjunction ; the elongation of Mercury at this time = 22. 18%'. 



VEJINIER. 



As instruments are now usually constructed, the following is a gene- 

 ral rule for finding the value of each division on any vernier. 



Find the value of each of the divisions or sub-divisions of the limb to 

 which the vernier is applied. Divide the number of minutes or seconds 

 thus found by the number of divisions on the vernier, and the quotient 

 will give the value of the vernier division. Thus suppose each sub-di. 

 vision of the limb to be 5' or 300", and that the vernier has 20 divisions, 



300 

 then -- - =. 15" = value of the vernier. 



VESTA. This planet was discovered by Dr. Olbers, of Bremen, 

 March 29, 1807. For its elements, &c., see Planets, element* of, 



ST7 T 3 



