CALIFORNIA ACADEMY OF SCIENCES. 343 



of May, made with his 10 1 inch reflector, equatorially 

 mounted : 



"At 7h. 25m. I commenced observing, and was astonished 

 at the faint appearance of the satellite, which was then about 

 15" from the limb of Jupiter. The first eye-piece applied 

 was a Huyghenian magnifying 215 diameters, and using the 

 full aperture of the reflector. A Kamsden of about 90 diam- 

 eters gave nearly the same result, but the faintness was more 

 decided; and with a power of 640 the satellite was scarcely 

 visible. 



" The atmosphere was much disturbed and therefore the 

 definition was blurred. Satellite IV gave about one-fourth 

 as much light as Satellite I, and was insignificant as com- 

 pared with III. I especially noted that Satellite IV had 

 a brownish color, something I had never noticed before. 



"At 8h. 05m. and 8h. 25m. I made similar observations 

 with similar results, using powers from 90 to 320 diameters. 

 The only change was in the growing faintness of the satel- 

 lite, which was then about one-half the magnitude of a faint 

 star 4' from the north, folio wing limb of Jupiter. 



"Numerous observations to 9h. ]0m. showed the decreas- 

 ing light of the satellite, when it became an ash or gray 

 color, and the satellite — now shorn of its rays — appeared 

 decidedly elongated in the direction of Jupiter's equator. 

 The length was apparently twice the breadth, and while I 

 have little faith in this proportion, on account of the dis- 

 turbed condition of our atmosphere, I am positive about the 

 elongation of the satellite's disk. But the most notable 

 phenomenon was the smallness of the satellite, appearing 

 one-third the size of Satellite I, when in the same position 

 near the planet's limb. 



1 ' The unsteadiness of the atmosphere prevented an accu- 

 rate noting of the time of contact of the limb of the satellite 

 with the limb of the planet, and my time may easily be one 

 or two minutes in error. 



