Lunar Sketches. 439 



yards, and often but a few inches, apart. To anyone familiar 

 with lunar features, the resemblance in these cases is so 

 striking, that it seems hardly possible at first to believe that it 

 is a mere coincidence ; but a little reflection will show that it 

 can be nothing more. There can be no analogy between the 

 operations of an intelligent and self- directing creature, bur- 

 rowing intentionally just below the surface, and the mechanical 

 working of a force which, obeying involuntarily the law of 

 creation, is compelled of necessity to burst through and 

 expend itself at once wherever the least resistance is offered. 

 Schr., indeed, and B. and M. have spoken of the lateral 

 working of elastic subterranean forces ; but it is very difficult 

 to conceive the modus operandi, especially in a case like the 

 present, where the tunnelling is so superficial, and the vertica] 

 resistance can have been so slight; unfortunately, it seems 

 equally difficult to suggest a less objectionable explanation. 

 We are here, however, struck with at least one analogy, which 

 is exemplified in innumerable situations and upon very varied 

 scales in the Moon; — the great tendency pointed out by Sir C. 

 Lyell in terrestrial volcanos " to shift their principal points of 

 discharge/ - '* — 1866, April 25. 5 |-inch achromatic. Terminator 

 through E. wall of Gassendi (64). "Have not some of these 

 pits become larger and deeper V — an idea, however, which 

 might arise from closer acquaintance, y pointed out a similar 

 illusion in the case of double stars, which seem to widen as we 

 are familiarized with them, and among such minute details 

 every precaution must be taken against involuntary deception. 

 — 1867, Nov. 18. 94--inch mirror. Terminator (in wane) close 

 to IAnn6. " Crater-chains so evident at this distance from 

 Terminator, that it is inconceivable how they should have 

 been missed by Schr/-' 



Copernicus. — Of this glorious object I have, of course, 

 many notices. — 1862, April 8. 5^-inch; Copernicus entered 

 something more than half its breadth. " The outer E. slope 

 of the ring showed a number of furrows radiating outwards, 

 as though the interstices of lava-streams." These, as we have 

 remarked on a former occasion, were discovered by Schr. (It 

 may be added that, considering that these furrowings, of 

 which he says he found scarcely any on the W. side, extend 

 down to the immediate neighbourhood of the crater-chain; 

 that the instrument employed was a powerful speculum of 

 about 9 inches diameter ; that the illumination must have been 

 favourable; and that the observation bears every mark of 

 care; it is very difficult to conceive how so curious an object 

 could have escaped his earnest and careful gaze, had it been as 

 fully developed, 1796, March 18, as it is now. A similar 

 * Memoir on Etna, " Philosophical Transactions," 1858. 



