104 TEAlfSIT OP TENU3. 



the exposure of the plate, and I determined to keep a sharp look 

 out for its formation at egress. Soon afterwards Mr. Vessey 

 came in and reported that the 4|-iuch had shown no drop at all." 



" Towards egress I referred constantly to the finder, that I might 

 be ready with a plate directly the drop became visible. When 

 Janssen plate No. 9 was in its place, and upon adjusting with the 

 finder, I observed no black drop, the planet appearing so far 

 within the sun's disc that I did not think it necessary to hurry 

 in order to catch the drop, and exposed the 'No. 9 plate, meaning 

 to get another in time. After taking out the plate, Avhich pro- 

 bably occupied twenty seconds, I went to the finder, and to my 

 astonishment saw that the drop had formed, appearing about as 

 long as one-third the diameter of the planet ; I hurried on the 

 next plate as much as possible, but a delay unfortunately of 

 a couple of minutes occurred before it was ready ; on development 

 it showed Venus a perfectly circular disc touching the sun's 

 limb." 



" I regret exceedingly that my eye was not at the finder during 

 the precise moment of the formation of the drop, but my duties 

 at the Janssen eye-piece prevented me from staying there more 

 than a few seconds at a time." 



" Referring to what I saw through the finder, I am convinced 

 that my observations, short though they were, have not deceived 

 me. I was thoroughly prepared, and on the look-out for the 

 phenomenon at egress, and I have not the slightest doubt that 

 any one using similar optical instruments w^ould undoubtedly 

 have observed what I did." 



If we turn now to No. 5 Janssen plate, and seek a photograph 

 of the drop, we find that photography, at least when aided by 

 Mr. Dallmeyer's beautiful lenses, refuses to acknowledge any 

 soich phenomenon ; on this plate there are sixty photographs 

 without a sign of the droj>, but all sho"wing a distinct band of sun- 

 light round the planet. It will be remembered that while this 

 was going on in the photoheliograph observatory, Mr. Vessey was 

 in the next place observing the phenomena of ingress with a very 

 fine 4j-inch equatorial, by Schroeder. With this instrument a 

 splendid view of the ingress was obtained, and he noted internal 

 contact at 12h. 23m. 4^507b. No. 5 Janssen plate was begun at 

 12h. 25m. 35-47s. ; and Mr. Hirst saw the drop at 12h. 25m. 30s., 

 or some time after egress had taken place, and it appeared to him 

 equal to one-third the diameter of the planet. Now we know it 

 was only Im. 45s. after observed ingress, and the photographs 

 prove that the planet was only one-twenty-second part of its 

 diameter within the sun's limb. 



Of course there is the possibility that the drop might have 

 broken between the time when Mr. Hirst saw it and the time he 

 began to turn the handle for the Janssen pictures ; but he passed 



