ASTRONOMICAL I'll K.N< i.MUN A AND PROGRESS. 



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,.f tin- appearance- oh-cncd, measures 

 r remarks appertain!!..: In each 

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'. October, 1*1.7. 



Flenrj J. Slack gives his observations of 



i during the eclipse of tin.- moon, 



:ibcr l:;i!i. IK' says : " As tin- shadow 



: dill'ercnt portions of the moon the 



darkiu '-s varii-il considerably, from a red coppery 



an inky purple. At times the visibility 



1 part- was very striking being tbe 



remarkable when the eclipse was at its 



-. As tin- moon passed out of tbe shadow, 



a brightening look place in opposite directions 



at the t\v<> edges ct' the linih, and bluish tints 



of brighter hue heeame eonspicuous, contrasting 



with the red-.'' On the contrary, Mr. Brown- 



\ing the same eclipse, says that be 



not detect any trace of color in tbe moon, 



what he ordinarily saw there; but bo 

 alludes to the narrow line of light which at all 

 time- hounded the edge of tbe moon during 



obscuration. Tbe same phenomenon 

 has been remarked by others, and Mr. Brown- 

 ing siigirots that it could bo explained if we 

 allowed to suppose that any vapor exists 

 in the atmosphere of the moon a supposition 

 which would not be justified by other appear- 



. M. Chacornac observed the same eclipse, 

 and says that the greater part of the lower 

 di-k, plunged into the shadow of the earth, was 

 of a ivd color, the portion near the limit of the 

 shadow being slightly violet. Between these 

 two extremes could bo seen yellow, orange, 

 blue, and green, resulting, he supposes, from 



^composition of solar light, by refraction 

 of the terrestrial atmosphere. Mr. Weston de- 

 scribes the prevailing colors as red, bluish, and 

 gray. The redness increased toward the dark- 

 ened edge of the moon. That the effects did 

 not result from any chromatic errors, was 

 proved by using different telescopes and powers. 

 The colors and their relative positions differed 

 entirely from those presented in the partial 

 eclipse of Fehniary, 1858. 



The Ki-cning Glow and Analogous Phenom- 

 ena. The Phil. Mag., of October, contains a 

 tran Nation from Pogg. Ann., of June, of a paper 

 by Dr. E. Loramel on this subject. The red 

 color of the sun in rising and setting is thus 

 explained by him. In the lower layers of the 

 atmosphere a number of fine corpuscles are 



uded; it is immaterial whether they be 

 solid (as for instance organic and inorganic dust, 

 the fine particles of carbon in smoke), or ex- 

 tremely minute water vesicles, as they are 

 probably formed by incipient condensation of 

 aqueous vapor. When the sun is near tbe hori- 

 zon, its rays must traverse a sufficiently long 

 path of the lower layers of the atmosphere to 



rience, to an appreciable extent, the dit- 

 fracting action of tbe groups of screens formed 

 by the small particles alluded to. Hence each 

 point of the sun must thereby appear reddish, 

 and surrounded by more strongly reddened dif- 

 Voi.. vii. 5 



fracted light. Of course, with a luminous gur- 

 faco such as the sun pre.ncnts, the red 

 mn-t lie more strikingly conspicuous than with 

 an isolated point of light, such as a star, in which 

 the reddish color at rising and setting i- -can-dy 

 noticed. Distant white surfaces like the glad, r- 

 and fields of snow of the Alps, and clouds near 

 the horizon, often show a purplish-red color, 

 while a white wall in the neighborhood of the 

 observer only appears of an orange red. The 

 light reflected from the former must, befoiv 

 reaching our eyes, traverse a sufficiently thick- 

 layer of air to experience a diffracting action 

 from the particles suspended in it. The author 

 thinks that the redness of morning and evening 

 is only to be ascribed to the action of aqueous 

 vapor in the atmosphere, when it appeal's es- 

 pecially brilliant, and the whole morning and 

 evening sky is of a fiery glow. If, on the con- 

 trary, the rising and setting sun simply appears 

 as a reddish disk, like the moon, in the horizon, 

 he thinks that tbe solid particles suspended in 

 the atmosphere are adequate to explain the 

 coloration. A similar appearance is exhibited 

 by the sun in the presence of a thick, yellowish 

 vapor, even when it is high in the heavens. 

 The red color, which, according to travellers 1 

 statements, is shown by the sun when the 

 simoom has raised the sand of the desert, is 

 explained by the same hypothesis. The spec- 

 trum of the setting sun has been lately more 

 accurately examined by Janssen. Toward the 

 violet end it appears continually weakened ; 

 the general enfeeblement of the more refrangible 

 rays depending (according to the author's the- 

 ory) upon the diffracting action of the finer 

 particles of water and dust in the atmosphere. 

 By the same principles he explains the fact that 

 ' imperfectly transparent media, such as smoky 

 ir'.ass, milky glass, smoke also, and a glass plate 

 blackened with soot, transmit the less refran- 

 gible rays more easily than the others. 



Observations of Venus, A writer, dating 

 from the Sheffield Scientific School (Am. Jour, 

 of Science, Jan., 1867), gives an account of ob- 

 servations made by him of the planet Venus in 

 close proximity to the sun, both before and 

 after her inferior conjunction in the previous De- 

 cember. At her nearest approach (9 h 52 ra A. -:.i 

 tbe planet was only 22" from the sun's northern 

 limb, and had the conjunction occurred a day 

 earlier, there would have been a transit. 

 Some days before the conjunction it was ap- 

 parent that the crescent formed more than a 

 semicircle, and three days before it, full 40 

 more by measrrenient. On the day before the 

 conjunction, it formed a complete circle, bright, 

 thin, and delicate (the crescent proper) on the 

 side toward the sun, but on the opposite side, 

 a faint line of light very difficult to be seen on 

 account of the strong light in the field and the- 

 atmospheric disturbance. Yet, by glimpses, 

 it was distinctly perceived as a ring, by 

 several observers, and constantly as more- than 

 three-fourths of a circle. The appearances 

 were similar, though perhaps a little better 



