298 Observations on the 



the eclipse, a remarkably large spot of light, of an irregular 

 figure and of a considerable brightness, about 7' or 8' within the 

 limb of the moon." It is rather singular, that the Earl of 

 Morton, who was making observations with a reflector, in the 

 apartment immediately adjoining, could not perceive this 

 appearance. "I lost this light" continues Mr. Short, "several 

 times : whether this was owing to shutting my eyes in order to re- 

 lieve them, I cannot tell ; when I first observed it, I called to my 

 Lord Morton, but he could not perceive it*." Many other 

 instances might be adduced similar to those now quotedf. On 

 former occasions, these appearances seem to have been almost 

 invariably observed about the middle of the eclipse; that, in the 

 present case occurred towards the commencement of the last 

 quarter : the only circumstance, however, materially different, 

 is, that in several, the streams of faint light were not seen, or at 

 least are not mentioned. 



To explain these phenomena, various hypotheses have been 

 framedl- Among the proofs of an atmosphere, the supposed 

 existence of lunar volcanos, as almost decisive of the question, 

 naturally holds a prominent place. The preceding appearances 

 accordingly are made to favour that opinion, and these isolated 

 F parks of light, have been attributed to volcanic effiects. The 

 evanescent nature of these appearances, their apparent great 

 extent, their having been hitherto visible, at certain phases only, 

 the lines of fainter light proceeding from them, are circum- 

 stances seemingly incompatible with such an origin. The 

 solutions opposed to this opinion are, however, not less liable 

 to objection. Since the appearances in question, have been 

 successively ascribed, to perforations in the body of the moon, 

 to igneous vapours in the atmosphere floating across the field of 

 vision, and to reflections of the solar rays from the surface of 

 the earth, which impinging on the summits of the lunar moun- 



* Phil. Trans, vol. xlv, p. 583. 



f Phil. Trans, vol. xxxviii, p. 332. fol. xli, p. 94, &c. ])lem. de I' Acad, 

 de Sciences. 



X See Sthroter's Selenotopogi-aphische Frugmente, Sec. 



