316 Br Pearson, On observations of the Transit [Jan. 29, 



light, was very marked; and had increased at 1*35 p.m. when I 



think it was at its maximum. 



I had little or no hesitation as to the time of the third, or 

 second internal contact. I think the outer edge of Venus was too 

 disturbed to exhibit the minute spots which I seemed to observe 

 in the morning. But still the planet seemed to descend fairly 

 upon the atmosphere without any mutual attraction of any kind, 

 and though the planet's disk could not then have been called any- 

 thing like a perfect curve or sphere, the actual contact seemed 

 perfectly regular ; and I do not think I had any hesitation as to 

 when it actually occurred : viz. at 



2 h. 41 m. 2 s. p.m. L. M. T. 



I was not entirely so fortunate as I might have been in taking 

 off the last external contact : owing to my mishap with my 

 chronometer in the morning, I had to trust for the time to my 

 watch, which I held in my hand : but just before the last contact 

 through inadvertence I had allowed the planet to get too near the 

 edge of the telescope to be viewed as it should be : so I took hold 

 of the slow motion handles to bring her more into the field of 

 view. Moving the telescope in this way causes a slight tremor in 

 the telescope itself : and when this had passed off, the indentation 

 caused by the planet's disk on that of the Sun had all but dis- 

 appeared; and I could not feel perfectly confident within two or 

 three seconds when the actual disappearance was complete. Still 

 I am sure there can be no great error about the time I give, viz.: 

 3h. lm. 15 s. p.m. L.M.T. 



as the vanishing segment of the planet had only a partial resem- 

 blance to the undulations on the edge of the Sun ; especially as 

 the momentary apprehensions that I felt do not seem justified by 

 the result. Had the period I assumed between the third and 

 fourth contacts been too long, a mistake would be probable ; but 

 as it was eleven or seventeen seconds shorter than the computed 

 time, and as I am sure that the Sun's disk had entirely recovered 

 its normal outline at the time I noted, I think that my observa- 

 tion may be taken as generally exact. Moreover, the longer the 

 period of transit, the shorter will be the passage across the Sun's 

 limb : and as my own period of transit is as long as that computed 

 by the French, and two minutes longer than that given by the 

 Nautical Almanac, I may be satisfied with the fact that my 

 passage across the disk is shorter than that anticipated by either 

 of these authorities. 



It has been a great matter of interest to me to see how nearly 

 my own observations would agree with the times of ingress and 

 egress announced in the Nautical Almanac and in the Connaissance 

 des Temps. I have therefore computed them for my place of 



