THE PLANET JUPITER.

317

In the Report of Professor Hough previously referred to, andquoted in the Observatory of October 1881, p. 303, we read: —

“ On July 3rd, 1880, the second Satellite during transitpassed almost directly over the centre of the Great Red Spot,when it appeared sensibly as bright as when off the disc.”

On November 1st, 1880, a transit of the shadow of the secondSatellite over the centre of the Red Spot was seen from theDearborn Observatory; and at the same time the transit ofthe shadow of the first Satellite over the disc of the planet.It is stated in the Report that “ the shadow of the Satellite,when fully projected on the Red Spot, was distinctly visible,but not quite as black as the shadow on the disc; proving thatthe Red Spot, although much less luminous than the disc, wasyet much more luminous than the shadow of the Satellite.”

On the other hand, Mr. Gwilliam mentioned in the Obser-vatory of January 1882, that he had seen the shadow ofSatellite No. 1 upon the Red Spot, and that he had forwardeda drawing of it, when so seen, to the editor. He has since verykindly informed the writer of this lecture that, when theshadow was half upon the spot and half off it, he could detectno difference in the colour of either part. He has also statedthat on November 26th, 1880, he saw Satellite No. 2 upon theRed Spot, when the effect was very curious, the Satelliteappearing as if surrounded by a bright halo , which partiallyobscured the dark-red tint of the spot. His observations weremade with a 6-Jr inch Calver speculum, and a magnifying powerof 200.

It will be noticed that the above-mentioned observations,being somewhat contradictory, leave the important questionof the self-luminosity of the Great Red Spot still undecided.

Upon the whole, we decidedly incline to the opinion that theplanet Jupiter is most probably in too highly heated a con-dition to be fit for habitation, apart from the fact that its greatdistance from the Sun, and the small amount of Solar light andheat received by it, would otherwise make it very difficult tobelieve that it can be a suitable abode for beings in any waysimilar to the human race. It is, nevertheless, quite possiblethat, at some still far-distant date, it will only retain sufficient