CALIFORNIA ACADEMY OF SCIENCES. 



341 



the 150 power on the 6.4-inch Equatorial; but I observed 

 the egress as closely as possible, using my watch, sloiv of 

 L. M. T. by comparison with mean time chronometer No. 

 5038=0m. 07s., viz.: 



I. Internal contact appeared to take place, 12h. 13m. 



II. First white excrescence visible, 12h. 16.7m. 



III. Satellite probably tangent to limb, 12h. 21.8m. 



IV. Satellite certainly clear of limb, 12h. 23.6in. 



V. Satellite one diameter clear of limb, 12h. 30m. to 

 12h. 31m. 



Hence, the egress apparently took place at 15h. 23.5m., 

 "Washington M. T., the almanac time being 15h. 23m." 



Mr. Hill has furnished the drawing for figure 2, to illus- 

 trate his observation. It is a reproduction of the original 

 in the note-book. 



^m • '" "-'^^Bmttsl^^^l 



Fig. 2— Feb. 24, 18S4— Jupiter at 19h. 54m. G. M. T. 



Mr. Burckhalter writes: — " Last night I observed the transit 

 of Jupiter's Satellite IV; the first contact was about two min- 

 utes later than the almanac time, and the satellite was about 

 eight minutes getting completely on the planet's disk. The 

 air was very steady and definition good. The satellite en- 

 tered the white portion just south of the great dark red belt. 



