OF ARTS AND SCIENCES. 315 



less dark than they had been, some of them becomiug so pale that they 

 could hardly be distuiguishcd. After a few days these enlarged spots, 

 which had become uumerous and encircled the planet, disappeared 

 altogether, leaving in their place a broad belt, having a strong resem- 

 blance to the equatorial belt, except that it was only half as wide, and 

 having a central cloudy white band enclosed on each side by a space 

 tinted with the delicate pink color which distinguishes the equatorial 

 zone. 



I shall here remark that every time I have observed great changes 

 in the configuration of the markings of the surface of Jupiter, they 

 were accompanied by an increase in the intensity of the rose color of 

 that part of the equatorial belt nearest to the place of disturbance. At 

 the time the black spots above desci-ibed made their appearance, simul- 

 taneously with the increase of intensity of the rosy belt, a slight tinge 

 of red was noticed under the black spots, in the northeast, this tinge 

 occupying a great portion of the area constituting the north polar cap. 

 This pinkish tinge went on increasing somewhat in intensity as well 

 as in extent until Nov. 1, when it culminated, then extending from 

 the first gray band north of the one where the black spots had formed 

 to the north limb. The pink tinge then gradually decreased in inten- 

 sity and in extent, and was last seen on the 24th of November, after 

 which it was confined to the northern pink belt already described. 

 The pink color of the equatorial belt towards the north seemed under 

 the same influence, since it culminated also in intensity on Nov. 1, 

 after which date it gradually decreased until it resumed the same 

 delicate tint with the other parts. 



The formation of this series of black sun-spot-like forms, with their 

 subsequent development into a broad pink-tinted belt, is very instruct- 

 ive, inasmuch as it shows us how the forces creating such belts are 

 acting. This action on Jupiter is not without some suggestive points 

 of resemblance to the action creating the similar openings of the 

 Sun's photosphere, which we call sun-spots. As we know, the sun- 

 spots not only have a tendency to form into groups, the axis of which 

 is parallel to the solar equator, — or, if it is not exactly so, it soon 

 attains tliis parallelism, — but, again, all the groups of one epoch keep 

 on the same parallel of latitude on each side of the equator. If on the 

 Sun the forces creating the spots should increase and continue for 

 some time with the same intensity as seems to be the case on Jupiter, 

 a continuous belt of spots would surround the Sun, and finally a broad 

 belt would result by the breaking up of the thin walls separating every 

 individual spot. On. the Sun, of course, the forces required to produce 



