EQUATIONS FROM FOEBES' OBSERVATION OF INGRESS. 223 



from the Second and third sets is 22 r- 990 ; hence the zero proper to apply to 

 the readings for distance of limbs is 22-990 - '057 = 22 r> 933. 



Using the tabular semidiameter of Venus as before, we have for the value 

 of one revolution of the micrometer screw 



_ 3i"-42+8r _ 5 ,,. g63 + .5 58 

 ^(26-902 ig'oag) 



The following equations have been formed with the values p = 15"'863 

 + -505 8 r ; R = 976"-80 ; r = 31"'42 ; and assuming the latitude and 

 longitude to be 19. 38'. 23" N., and 10 h . 24 m . 2 8 '7 "West, respectively. The 

 revised longitude being 10 h . 24 m . l s> 7 W., 8 t = l s> on this account. The 

 correction to the Transit-Clock has been assumed to be + 32 S< 03. 



G. L. T. 



