96 TEANSIT OF TE>"US. 



Next, to the times of observation ; and for the purpose of con- 

 venient comparison I have arranged all in a tabular form, and 

 approximately corrected them for difference of position, and put 

 all into Sydney time. I confess when I saw the gradual 

 phenomena of the transit myself I did not expect such a satis- 

 factory agreement between the times of observation as some of 

 the results show ; and if 4 j seconds could be taken (as it was 

 by astronomers at home) as a fair estimate of the probable 

 uncertainty of observed time at one station, when a definite 

 phenomenon like the breaking of the black drop had to be 

 observed, I think we, under our no black drop difficulties, may 

 congratulate ourselves that the differences are in most cases so 

 small. 



Only three out of thirteen observers took the time of first con- 

 tact, and they were evidently a few seconds, probably about ten, 

 late. Such, at least, was my own impression at the time, for 

 Venus had made something more than contact : it was a small 

 notch in the sun's limb. 



My time is llh. 55m. 23-OOs. 



Mr. Lenehan llh. 55m. 30-34?. 



Woodford — Mr. Vessey ... ... llh. 55m. 12'96s. 



These times show a very satisfactory agreement, especially 

 when the difficulty of seeing external contacts is taken into 

 account, and the fact that in 10 seconds of time Venus would 

 only encroach about half a second of arc on the sun's limb, a 

 quantity not easily seen, and equal to one-thousandth part of an 

 inch seen at a distance of 3-1 feet. For second contact I think 

 there can be no doubt that different phases of the phenomenon 

 were taken by observers according to the different effects pro- 

 duced by the expected black drop, which up to that time had a 

 very tangible existence for all of us ; and as it is very important 

 that the exact phenomenon taken by each observer as internal 

 contact should be on record, I will here quote from the reports, 

 beginning at Eden. 



Mr. Scott took the time when " he saw the partial obscuration of 

 the sun's limb by the planet's atmosphere gradually diminishing 

 until it disappeared altogether at 12h. 23m. 7'90s." which I take 

 to mean the completion of the sun's outline, the same phase which, 

 as will be presently seen, I and others took for complete ingress. 



Mr. MacDonnell took the time when " the light seemed to be 

 going in and out several times, and prevented any accurate deter- 

 mination of complete ingress as 12h. 21m. 3170s.," but he is 

 convinced he was 15s. late, making the time 12h. 24m. 19'70s. 



At "Woodford Mr. Vessey took the time when Venus appeared 

 to touch the sun's limb, or when the two limbs were tangential, 

 (See diagram 5.) Time, 12h. 23m. 45'07s. 



