60 



TRANSIT OF VENUS, 1874. HONOLULU. 



contact, I took out the double-image eye-piece, and immediately inserted a 

 negative eye-piece of power 130, furnished with a neutral tint sliding wedge. 

 The telescope was slightly disturbed in doing so, but that did not prevent 

 me from getting it re-adjusted and sharply focussed in 32 seconds after the 

 last reading of the micrometer, when to my astonishment I saw a completion 

 of light round the planet, perfectly distinct, and such as I should have said, 

 from previous model practice, was immediately after contact. This is the 

 time recorded. I remained looking at it for about two minutes, but could 

 see no instantaneous phenomenon of contact, no black drop, nor anything 

 resembling the model. I noticed that this light did not appear to thicken as 

 I should have expected for a considerable time after that recorded ; but as I 

 considered, from my previous experience (with the model), that the contact 

 had occurred, and was unable to get, accurately, any further change until 

 the planet was visibly on the Sun, I cannot say that the time as noted is at 

 all satisfactory. 



The double-image micrometer was then replaced and 33 limb and 20 

 diameter observations taken. These were to my mind as good as any I could 

 have taken on an average day at the model. 



The planet appeared circular, although the edge vibrated considerably. 



20 h . 19 m . 23 s . External contact first perceived. Time by Equatoreal 

 Clock [see page 46]. 



4^-inch equatoreal double-image micrometer measures of the diameter of 



Venus.* 



Micrometer Readings. 



5'ogi 

 5-088 

 5'o62 

 5-o8o 



5-i55 

 5-J25 



14-889 

 14-900 

 14-881 

 14-911 

 14-909 

 14-860 



4^-inch equatoreal double-image micrometer measures of cusps. Time 

 counted from chronometer C by Lieutenant Oldham, E.N. 



* The reading of the micrometer for coincidence of the optic axes of the two halves of the 

 divided lens was approximately io r 'o. Readings greater and less than i o r o indicate that (ho 

 movable half-lens was on alternate sides of the fixed half-lens. 



