66 



ASTRONOMICAL PHENOMENA AND PKOGEESS. 



seen, the day after the conjunction. At 2 h 15 m 

 p. M., the planet was readily found with a 

 portable 5-foot Clark telescope of 4 inches' ap- 

 erture, by taking a position in the shadow of 

 a chimney. The complete ring and the faint 

 portion of the crescent proper were both dis- 

 tinctly seen, better than they had been through 

 an equatorial, except in cases where the sun' 

 was intercepted by a passing cloud. The best 

 view was that taken at moments when a clpud 

 obscured the sun, leaving the planet full in 

 sight. The background was then compara- 

 tively dark and the thread of light around the 

 limb opposite to the sun was perfectly distinct 

 and complete. The northern portion of the 

 crescent proper, however, did not diminish 

 uniformly in brightness or apparent thickness 

 toward the cusp, but a considerable space, be- 

 tween 25 and 30 degrees from the vertex to the 

 left, by estimate, was very perceptibly fainter 

 than a like portion of the circumference next 

 beyond toward the right, whence it gradually 

 narrowed to the faint line of light before men- 

 tioned. On the fourth day after the conjunc- 

 tion, the cusps had receded to 30, and three 

 days later to 22, beyond a semicircle. The 

 powers used were from 80 to 200 on the equa- 

 torial, and 90 on the smaller telescope. These 

 observations are regarded as having a bearing 

 upon the question of the atmosphere of Venus. 



Mr. Levander, of Canonbury, on the 20th of 

 October, at 2 h 50 m , saw Yenus when only 

 about 25 m 50" east of the sun and 9".6 in 

 diameter. He used a IJ-inch telescope mounted 

 equatorially by himself. A cloud obscured the 

 sun at the time. 



Mara in Opposition. Mars, during his op- 

 position in January and February, 1867, is 

 the subject of a paper by John Browning, 

 published in the Int. 01)8. of September. He 

 observed the planet on favorable nights from 

 January 8th to February 24th, through an 

 equatorial reflector, having a silvered-glass 

 speculum 8f inches in diameter, with a power 

 used of 300 to 600. The color of the body 

 of Mars he found to vary from rose-madder 

 to burnt ochre, appearing ruddiest when there 

 was most mist in our atmosphere. The com- 

 parative absence of the ruddy tint toward 

 the edges of the disk has been ascribed 

 by Mr. Norman Lockyer to the presence of 

 clouds in the planet's own 'atmosphere; but 

 Mr. Huggins, in a paper on the " Spectrum and 

 Color of Mars " (Monthly Notices, Boy. Soc., 

 March 8, 1867), refers the absence of color to 

 some peculiar effect of the surface of the planet 

 itself. Mr. Browning supports this view, and 

 accounts for the appearance by supposing that 

 mist stops the most refrangible rays of light ; 

 that is those toward the blue end of the spec- 

 trum, whose waves have the greatest velocity, 

 the red light thus being allowed to preponder- 

 ate. Observed under these conditions, the 

 edges of the disk appear Naples yellow, the 

 centre orange tinged with burnt ochre, while 

 the parts near the south side are whitish, with 



a tinge of salmon color. The color of the dark 

 markings on Mars has usually been described 

 as greenish or bluish-gray ; to Mr. Browning 

 they appeared of the latter tint. In conse- 

 quence of the effect of irradiation, he was not 

 able to make out satisfactorily the outline of 

 the north polar ice. lie frequently saw faint 

 white spots on the disk, and as they ap- 

 proached its edge they increased in brilliancy, 

 until, when near the extreme edge, they al- 

 most rivalled the polar snows in whiteness. 

 They were generally nearly circular in form, 

 and always appeared in the region of the equa- 

 tor. Sketches of the planet taken at the same 

 time by Mr. De la Rue and Mr. Dawes are 

 similar in many of their markings to those of 

 Mr. Browning ; and there is considerable re- 

 semblance between his and one of Father 

 Secchi's sketches, but Mr. B. cannot trace any 

 likeness between his own views and those of 

 Beer and Ma'dler. With regard to the point 

 that no flattening of the poles could be detected 

 by any of the observers, he remarks that al- 

 though if the sphere of the planet were oblate 

 to the extent of one-sixteenth or one-tenth of 

 its diameter, as in the case of Jupiter and the 

 globe of Saturn, the flattening might be easily 

 discerned, yet if it should not exceed in propor- 

 tion that of the earth, as would probably be the 

 case from its having nearly the same axial ve- 

 locity, then we could not hope to perceive it, 

 for under such circumstances the flattening of 

 the disk would not exceed 12 miles, and this, 

 when the planet is nearest to us, would sub- 

 tend an angle of only ^ of a second. From 

 the observed recurrence of spots, Mr. Brown- 

 ing estimated the period of the planet's axial 

 rotation at 24" 38 m 8", which is less than Sir 

 ' William Herschel's estimate; but Beer and 

 Ma'dler, who have observed the largest number 

 of rotations, give the period at 24 h 37 m 23 s . 

 Speculating upon the question whether Mars 

 has a satellite, the writer says : " If such a sat- 

 ellite existed of a size proportionate with our 

 moon (to the earth), it would be one-quarter 

 the diameter of the primary, and we might ex- 

 pect it to be easily visible ; but should a satel- 

 lite exist not exceeding in size proportionately 

 the second satellite of Jupiter, it would only bo 

 visible in very powerful instruments ; still it 

 would not, I think, have escaped the notice of 

 the persistent observers who have searched for 

 it, hitherto, vainly." 



In Mr. Huggins's paper on the spectrum of 

 Mars (already referred to), he says that it does 

 not appear probable that the ruddy tint which 

 distinguishes Mars has its origin in the planet's 

 atmosphere, for the light reflected from the 

 polar regions is free from color, though that 

 light has traversed a longer column of atmos- 

 phere than the light from the central parts of 

 the disk. It is in the central parts that the 

 color is most marked. He regards all the evi- 

 dence as supporting the opinion that the 

 planet's distinctive color has its origin in the 

 material of which some parts of its surface are 



