REPORT OF MR. J. W. NICHOL. 59 



Hence the corrected inferred times are 



Tupman 7 h . i8 m . 8 S< I G.S.T. 



Nichol 7 h . i 8 m . 1 1 3 7 



While the telescopic contact was certainly passed 



at 7 h . i8 m . o 9 . (Tupinan and Noble). 



These results are in perfect accordance with those obtained by Colonel 

 TENNANT at Roorkee, who found the time of contact inferred from the cusp 

 measures to be 10 s- 2 later than the telescopic time of contact. 



I may remark here, that although these cusp measures appear to be very 

 reliable, there is a very serious discrepancy between the observations at 

 Honolulu and at Roorkee, amounting to 17 or 18 seconds of time on any 

 reasonable assumption of the solar parallax. 



I have thought it not worth while to make a similar comparison with the 

 measures of limbs, the co-efficient of 3r being very large. 



REPORT OF MR. J. W. NICHOL. 



The observation of external contact was taken by me with the Naylor 

 6-inch equatoreal telescope, with power of 145, and neutral tint glass. 



Lieut. Oldham, R.N., took time for me, counting seconds aloud and making 

 the entries in the note-book. 



The limb of the Sun was very rugged. 



The first time recorded was when I perceived a definite indentation on the 

 upper limb of the Sun, and the contact must have occurred, from the size of 

 the indentation, 30 seconds to a minute before that time. 



I then changed places with Captain Tupman, and going to his 4J-inch 

 equatoreal inserted the double-image micrometer eye-piece, the power of 

 which was about 150. The planet was then accurately focussed, brought 

 into the middle of the field, and the two images adjusted to equal intensity. 

 Twelve observations for diameter were taken, when the planet appeared to 

 be fully half way on the sun. The method of bisection was to place the two 

 images so that they separated and joined alternately as nearly as possible 

 to the same extent by the continued vibration of the air. By this time the 

 cusps were approaching, and the phenomenon appeared almost the same as 

 the model, except that the planet seemed somewhat brighter by contrast. 



Seventeen observations of cusps were taken. The definition of the ex- 

 tremities of the cusps was as good as on an average day at the model, and I 

 found no difficulty in just getting them to touch. 



"When the micrometer reading had diminished to 12M52, knowing from 

 previous model practice that I had more than a minute to spare before internal 



i 



