1870.] Astronomy. 393 



minutes of total obscuration. This remark applies not only to 

 general observation, but in an especial manner to those extremely 

 delicate spectroscopic and polariscopic observations which are re- 

 quired in the present instance. 



Captain Noble, observing Venus near her inferior conjunction, 

 found the body of the planet projected very distinctly as a dark 

 disc on a light background. " The difference of tint from that of 

 the surrounding sky was evident," he says, " the instant Venus was 

 regarded." This observation, though not new, deserves special 

 attention just now that the nature of the solar corona is being so 

 much inquired into. It shows beyond all possibility of question 

 that there is some light which comes from regions beyond the 

 planet ; in other words, that there is just such illumination beyond 

 Venus as we should expect to find if the corona is a solar appen- 

 dage. It seems amazing that in the face of such evidence — with 

 Venus actually projected as a dark disc on some illuminated region 

 beyond her — any astronomer should believe the light of the corona 

 to come from the glare of our atmosphere some hundred miles or so, 

 at farthest, from the earth. 



Mr. Browning invites attention to farther changes in the form 

 and colour of Jupiter's belt. The ochreish-yellow which had been 

 so marked during the winter months of 1869 had, on January 31, 

 become much fainter and of a duskier hue, being also confined to 

 the northern part of the equatorial belt, instead of covering the 

 whole of it as had before been the case. On March 10th, he found 

 the tawny-yellow colour again extending over the whole of the 

 equatorial belt, which had become broader than he had ever before 

 seen it. This belt had a very dark band on the south, and a 

 narrower dark band on the north ; beyond each of these being a 

 brilliant white belt. It will be interesting when the planet again 

 returns to our skies (towards the end of the year) to observe whether 

 the striking outbreak of colour has passed away or increased. The 

 planet will not rise to a great height on the meridian, but the cor- 

 recting eye-piece ingeniously contrived by Messrs. Airy and Simms 

 will render observation at low elevations a very different matter 

 from what it used to be. 



At Mr. Hind's suggestion, Mr. Plummer, of Mr. Bishop's Ob- 

 servatory at Twickenham, has re-examined the orbit of the comet of 

 1683. He has been able to show that, instead of the ellipse calcu- 

 lated by Clausen, the orbit of the comet is probably parabolic or 

 nearly so, so that there is very little probability that this famous 

 comet will quickly return to the sun's neighbourhood. 



Professor Wolf has continued his researches into the solar spot- 

 period. He finds that the observations made in the years 1864-69 

 supply clear evidence in favour of his theory that the spot-period is 

 one of lly- years. But the most interesting part of his communi- 



