342 CALIFORNIA ACADEMY OF SCIENCES. 



I observed the satellite for about five minutes after the in- 

 ternal contact, and saw nothing unusual, but on the contrary- 

 could only see the bright satellite on the white belt with 

 difficulty. At the almanac time of II oc. dis. (8 hr. 53 m. 

 L. M. T.) Mr. Wm. H. Lowden took the instrument to ob- 

 serve the phenomenon, and he at once announced that there 

 was a shadow of a satellite on the planet. Thinking he 

 must be mistaken, I again looked and found, as he had said, 

 a black spot "as black as a drop of ink," and I then noticed 

 that this spot occupied about the position of the satellite 

 then in transit. I then thought I must have made an error, 

 but on referring to the Ephemeris, I found that no shadow 

 could be on at that time, and that consequently it must be 

 the fourth satellite projected on the disk as a black spot in- 

 stead of the usual bead of light. This phenomenon so occu- 

 pied our attention that the oc. dis. was allowed to pass un- 

 noticed. Thereafter we watched the spot at intervals for 

 nearly an hour, during which time it remained absolutely 

 black." 



It will be noticed that Mr. Burckhalter observed the sat- 

 ellite enter as a white disk on the body of the planet, and 

 that it was subsequently seen black. He observed with a 

 1(H inch Brashear reflector, but does not report the magni- 

 fying power used, and has furnished no drawings. 



The President then referred to the earlier notices of these 

 or similar phenomena. 



THE DARK TRANSIT OF JUPiTER'S SATELLITE IV. 



BY PROF. GEORGE DAVIDSON. 



[Meeting of June, 1885.] 



The President said that he had transcribed from the 

 memoranda of Mr. Charles Burckhalter, of Oakland, his 

 observations of the transit of the IV Satellite on the 21st 



