FORBES' OBSERVATION OF INGRESS. 221 



Time by the 

 Transit-Clock. 



has 



20. 50. Mr. Lloyd began to count seconds aloud from inside the 



transit-hut, but the Sun became obscured by clouds. 



21. 8. The planet is well on. The clouds are partially dispersed. 



The double-image-micrometer inserted ; the following 

 distances of limbs measured : 



h m r bmi i 



21. 9. 3o 21'OOD 21.14.11 20*346 



10. 1O 20'80O 14.66 2O'l54 



11. 3i 2o'6o2 1 5. 23 20*209 

 12.23 2o - 568 16.40 20-029 

 i3. 5 2o'3i3 45* 19-866 

 13.43 20-486 ig. 14 ig'756 



* Minute not recorded. 



The measures of distances of limbs were discontinued when that distance 

 was about equal to the diameter of Venus, as shown by the overlapping of 

 the two images of Venus. 



So far as I can judge, the observations are sufficiently regular to lead to the i 

 belief that the micrometer was working well, in spite of a fall it had pre- 

 viously. 



Measures are now taken of the diameter of Venus, to serve as a measure 

 of one revolution of the micrometer-screw, and to determine the zero 

 reading. 



Micrometer Readings. 



18-961 

 i8-g3g 



Considerable boiling. Images cannot be made equally bright by means of 

 the adjusting screw. 



Images made equally bright by revolving the body of the micrometer. 



Micrometer Readings. 



r 



ig-o33 

 i8- 9 g 9 

 ig - o55 



F F 2 



