74 The Transit of Mercury on November 12, 1861. 



twenty minutes in retreat. I forgot this ; and therefore when 

 I descried the planet as above, at 8 a.m., I supposed I had 

 still an hour and eighteen minutes in which to watch the tran- 

 sit, because it was to be over at 9h. 18m. This 9h. 18m., how- 

 ever, was but 8h. 53m. of Dublin time. Yet I have not to regret 

 any idleness during those fifty-three minutes, the like of which 

 are not to happen to me again for seven years, if ever again. 

 I sketched the sun and the planet and s r spots repeatedly. 

 I viewed them directly and by projection ; and I called just one 

 " witness to my Strange Site in the heavens," as the coastguard 

 man wrote, who discovered Donates comet, somewhat early in 

 its career of celebrity. That witness came in good time to see 

 it appearing when projected on paper, exactly as shown in the 

 illustration which heads this narrative. To show it in this 



manner, the telescope was 

 arranged as in Fig. 3, 

 the window shutters be- 

 ing partly closed, and the 

 curtains drawn, to add 

 brilliancy to the effect. It 

 struck me as a very curi- 

 ous circumstance that it 

 should ever be possible to 

 bring the veritable shadow 

 of a "planet into one's own 

 room ! 



The figure heading this 

 narrative gives a small por- 

 tion of the solar disk as it 

 appeared when projected 

 on paper ; it was not only 

 inverted but reversed ; that 

 is to say, it was turned 

 upside down, and shown, 

 as in a looking-glass, left 

 for right. The edge of the disk is to be imagined in constant 

 undulating motion. 



The sun, as observed directly with the telescope at this time, 

 was as in Fig. 4. And now the planet rapidly neared the edge 

 of the disk. I regretted much the low power of the telescope, 

 as it prevented my looking out for some curious effects of 

 irradiation which are said to have been observed on the entrance 

 and departure of the planet during former transits. When the 

 upper outline of the planet touched that of the sun (Fig. 5), I 

 watched it intently; noting, however, nothing except that it 

 took a considerable time to slide completely out of sight. It 

 appeared as a notch on the sun's edge, becoming smaller and 



Fig. 3. 



