ON THE VISIBILITY OF VENUS — CAMERON. 155 



clear, and, liaving determined by a sun-observation that about 

 10 minutes after sunset Venus should be close to a certain chim- 

 ney on a neighbouring house, I looked there at that time and saw 

 her. A note made at the time says, " 6.30 sun's centre in horizon, 

 6.42 Venus distinctly with eye." This was 26i days after 

 superior conjunction, the elongation was 6|°, the phase X the 

 brillliancy 24. This is the best observation I know of near 

 superior conjunction, and is the best near either conjunction so 

 far as smallness of elongation is concerned. It might have been 

 even better, had it not been for the cloudy evenings on the 

 previous tive days. At Marseilles the weather was much worse 

 than here, and it was not until two months later that M. 

 Bruguiere got his first eye-glimpse of Venus after this superior 

 conjunction. 



The next one, and the last one to date, occurred at noon on 

 September 18, 1.S91. The earliest observation after it that I 

 have heard of was made by Miss Beatrice Tooker of Yarmouth 

 on October 17, 29 days after conjunction ; but this was with an 

 opera-glass and so we can't count it here. The declination con- 

 ditions were not as favorable for early eye-observations as on 

 the previous occasion, and my eyes were not in good condition 

 at the time for looking into a sunset sky. As a matter of fact 

 I did not look for Venus at all until the evening of November 

 9, 52 days after conjunction, and by that time of course she 

 showed up at once, and only live minutes after the sun's upper 

 limb had disappeared below the horizon. 



There is (juite enough evidence here, I think, to show that our 

 provisional limit of 20° and 78 days can be reduced a good deal. 

 It would perhaps be going too far to say, on the faith of my 

 observation of March 16, 1890, that we can always see Venus in 

 clear weather when only 26 days and 6" out from superior con- 

 junction ; and yet that oljservation was the only one of mine, 

 made near this conjunction, that gave Venus a fair chance to 

 show what she could really do for us in this line. To be quite 

 safe, however, let us allow a liberal margin of 50 per cent, or 

 so to cover adverse declination conditions, and we shall have as 



