72 The Transit of Mercury on November 12, 1861. 



telescope (by Tulley and Sons) of two inches' aperture, and had 

 during the week preceding the transit accustomed myself to 

 observing the sun's disc both directly and by projection (as in 

 Fig. 3). The window of my room most happily commanded a 

 view of the eastern heavens, with a tolerably unobstructed 

 horizon. There were, indeed, a few trees in the way ; but they 

 were low, and concealed only that part of the sky where the 

 density of the air would in any case render objects indistinct. 



The afternoon of November 11th promised well. The moon 

 truly " walked in brightness," and the telescope showed " Plato," 

 " Pico," and other lunar heights, with their black shadows in 

 satisfactory sharpness. So I hoped for a fine morning, and 

 having never seen a transit of Mercury, anticipated the pleasure 

 with some of the eagerness felt by old Gassendi, the first 

 observer of such a phenomenon.* 



On November 12th, I looked out at about a quarter to seven 

 in the morning. Delightful sight ! the sky was perfectly cloud- 

 less. The brightest stars were disappearing in 

 the increasing light of morning, but Jupiter and 

 Saturn still glittered in the south-east. The light 

 of Saturn was nearly ' ' burnt out in the pale blue 

 air," yet its exquisitely delicate ring could still 

 be detected, giving more the idea of a film than 

 Fi c i of a definite line on each side of the planet.f 



While Saturn remained visible, I felt I had time to spare, 

 but when he disappeared, and even Jupiter's light waned, then 

 I knew the real work of the morning was coming. Redder 

 and rounder grew the glow of light exactly behind a small tree. 

 Soon it sparkled through the branches, the sun had risen ! and 

 while yet only a semicircle, my telescope was there to watch it, 

 its outline waving like rippling water. J But the disk rose 

 grandly from branch to branch. Very curious was the effect, 



* On November 7th, 1631, this transit, predicted two years previously by 

 Kepler, was observed by Gassendi, Professor of Mathematics in the University 

 of Paris. The next transit of Mercury which was observed, was on November 3rd, 

 1651. A young Englishman, named Shakerley, had found by calculation that this 

 transit would be visible only in Asia, and he proceeded to Surat in India for the 

 express purpose of witnessing its occurrence. He was successful in the object of 

 his pilgrimage ; and the anecdote remains as one of the romantic episodes of 

 astronomy. 



t The ring of Saturn became edgewise to the earth, though not yet so to the 

 sun on November 23rd. It was, therefore, barely visible on November 12th ; and 

 on November 23rd I observed Saturn as a round disk without the slightest trace 

 remaining of its ring. 



J The rippling motion observable on the outlines of the sun, moon, and other 

 heavenly bodies, is quaintly but well described by Derham. His descriptions, from 

 original observations, are interesting from their freshness and truth ; ever fresh 

 and new, like the grand objects they describe. I quote from " Astro-Theology," 

 sixth edition, 1731 :— "There are some certain transient Roughnesses and Uneven- 



