VENUS IN DAYLIGHT — CAMERON. 351 



plein jour." I don't know whether M. Trouvelot's " en plein 

 jour" is to be taken in this extended sense or not ; but he may- 

 use the phrase so, and that is why I have mentioned these sunset 

 observations of mine in connection with his limit. 



For myself, I don't recognize either the distinct one of March 

 1890, or the doubtful one of May 1893, as having been made 

 " in daylight." This phrase in the title of this paper is meant 

 to include only the time while the sun is above the horizon, and 

 ■especially the two or three hours in the middle of the day. 



For this time of day I have not yet mentioned any observation 

 made near superior conjunction, and I have none to mention that 

 I consider good. Once, for a few minutes, I had high hopes of 

 having a splendid one. It was near 1 in the afternoon of May 

 11, 1893. Venus had been in conjunction only 9^ days before. 

 She was following the sun's east limb at a distance of only 2|°. 

 The seeing was not the best, but it was very good. She was 

 very easy in a field-glass, and quite distinct in an opera-glass (of 

 which more anon), and for a few minutes I hoped to catch her 

 with eye alone, but did not. I am sure that I pointed my eye at 

 the exact spot, I am almost sure that she was fully as easy as on 

 July 6, 1892 ; but I am not sure that I took proper care to focus 

 my eye for a very distant speck. After the 11th, I have no 

 record of a good sky near noon until the 31st, and then my eye 

 failed again. And again in a fine sky on June 1st. The mid- 

 day weather was bad between the 1st and the 7th. On the 7th 

 — " 12.20, Venus very easy in opera-glass, eye no good ; 12.57, in 

 eye in a splendid bit of blue sky all washed clean of every par- 

 ticle of cloud, a good long steady look, far more satisfactory than 

 any eye-look in evening so far, wisps of light cloud over her just 

 before and just after observation." 



But this was 36 days after conjunction, and the elongation 

 was nearly 10°. 



This is the best that the atmospheric conditions have allowed 

 me to do near superior conjunction, but of course it is not at all 

 the best that can be done. When only 5^ out at this conjunction 

 Venus is five times as bright as when my eye saw her at 7° 

 elongation near inferior conjunction. This diflference in bright- 



