The Transit of Mercury on November 12, 1861. 73 



when, the sun itself out of focus, I allowed it to project on 

 paper the shadows of the intervening branches. Every twig, 

 and every lingering ash-leaf, parched by the sere winds of 

 autumn, but not yet fallen to earth, were shown in singular 

 sharpness and waving in the breeze. Curious, too, when looking 

 directly at the sun through the dark glass of the telescope, 

 anxiously waiting its arrival behind a somewhat thinner part of 

 the tree, a little pert tomtit or robin hopped to and fro, uncon- 

 scious that he too was performing a transit across the sun's 

 disk for my benefit. The bird was out of focus, the sun was in; 

 and a few minutes later, came to more thinly crossing branches ; 

 (Fig. 2), and there, on his disk, was the unmistakeable Black 



Fie. 2. 



First View of the Planet Mercury, on the Sun's rising above some branches of 



a tree. 



Disk of Mekcuey! It was nearer to the edge than I had 

 expected to see it, and (truth to tell) it was very small; but 

 exactly of the size which I knew it would appear, judging by 

 the measurements of the sun, and of Mercury and the other 

 planets, always given in Dietrichsen and Hannay's Almanacs. 



The difference of longitude between Greenwich and my 

 position (Kingstown, near Dublin) is about twenty-five min utes 

 of time. Hence, when the sun rose at Kingstown, the planet 

 had not only accomplished half of its transit (as was the case 

 two minutes after sunrise at Greenwich), but had been more than 



nesses on the Limb caused by Vapours, especially when the Moon is near the Hori- 

 zon, and in windy and some other Weather. At which Times, the Motion of the 

 Air and Vapours makes a pretty Crispaiiou and Rouling, like Waves on the Moon's 

 Limb, which have the appearance of moving Mountains and Valleys." 



