396 Miscellanies. 



sion has yet been distinctly improved, for the purpose above indicated ; 

 nor — however probably that circumstance may be the result of a too 

 limited information on my part — have I seen reason to expect that the 

 one just at hand is likely to be so improved, otherwise than incidentally 

 and very imperfectly. It will be impossible for the astronomers, intent 

 as they must be upon telescopic observations, to do full justice to the 

 phenomenon in question, and almost equally impossible for any other 

 man who shall not have anticipated in his reflections the specific aspects 

 to which the attention ought to be essentially devoted. 



Before quitting this topic, may I be indulged in making an inquiry 

 that naturally grows out of it ? Is not the light which, in a total eclipse 

 of the moon, makes her dark face visible to us, derived, in a greater 

 measure, from this equatorial nebula of the sun, than from the refrac- 

 tive effect of the earth's atmosphere ? If the intensity and extent 

 of the zodiacal effulgence shall be detected at the occurrence of the 

 coming eclipse, or by any other means, it may be possible to reply 

 very satisfactorily to this inquiry. I would not unhesitatingly assume 

 that a reply substantially satisfactory might not be derived from facts 

 already well known. I must own that, hitherto, I have not even under- 

 taken to speculate concerning the amount of illumination, at the moon's 

 sui'face, due to the terrestrial atmosphere, — a question which would 

 seem, at first view, to be of moderate difficulty, if only the dispersive 

 and refractive powers of common air are exactly ascertained. 



But I pass on to some suggestions respecting a phenomenon of a 

 different class. To observers just within the path of total obscuration, 

 — and perhaps, very transiently^ to those situated deeply within it, — 

 the telescope will probably reveal a fine thread of light, edging some 

 part of that dark limb of the moon which is in near proximity to the 

 sun's corresponding limb. I infer this probability from a similar as- 

 pect, — which may indeed have been observed at other times, and re- 

 corded, although I have no knov/ledge that it has been, — that was wit- 

 nessed by myself, through an excellent instrument, from the station of 

 New York, on the occasion of the annular eclipse of 1838, — or rather 

 the eclipse which just failed to be annular, at that station, on account, 

 possibly, of an irregularity in the moon's outline. In any event, it 

 must be rare that the phenomenon under consideration can be exhibited 

 so strikingly as it was on the occasion alluded to, from the very cir- 

 cumstance of my station being at or near the limiting boundary, upon 

 the earth's surface, of the annular aspects. On that occasion I noticed, 

 several minutes before the time of nearest completion of the ring, the 

 fine cusps of the sun's unobscured crescent prolonged by a hair-breadth 

 line of brightness, totally diverse, in color and intensity, from the sun's 

 disc. As the cusps approached, the line -or thread of light in advance 



