on the Planet Venus. 
165 
log. dist. of the earth from o = 0,005628 
log. dist. of Venus from o = 9,860276 
log. tang. 10,145352 
= 54 ° 2 4 > 5 °" 
subtract 45 o o 
remain 9 24 50 
log. tang. 9 0 24' 50" - 9> 21 9579 
log. tang. 87 59 55 - 11,4 56615 
log. tang. 10,676194 
half difference = 78° '5 53" 
half sum - = 87 59 55 
angle at Venus - = 166 5 48 
angle at the earth = 9 54 2 
compl. of the angle at ? = 13 54 12 
Now, as I have stated above, the projected extent of the twi- 
light measured 10", putting the semidiameter of Venus == 30" ; 
and, as I then measured that extension perpendicularly on the 
line of the cusps, these 10" may be considered as a sine, and 
so the arch will amount to 19 0 28'. Then 
log. sin. 13 0 54' 12'' 9, 380725 
log. sin. 19 28 - 9,522781 
8 , 9 ° 35° 6 
= 4 ° 35 ' 34 " 
To so much, therefore, amounts, according to my second 
