May 14, 1885] 
NATURE 3 
= 
rere) 
each {rotation ; and, if we amalgamate the two preceding 
periods, from November 7 to November 27, we get a 
mean of gh. 49m. 38°96s., which is closely accordant. 
In the forty days, November 21 to December 31, the spot 
gained 65'1m. = 39°7° upon Mr. Marth’s central meridian 
obably recurrent markings on Jupiter. I. 1 
IV. 1870, January 23, 8h. 2om. (Gledh 
identity of the spots observed on January 13 and 27; so 
that in the fourteen days it lost nearly 11,000 miles, 
which is greater than the rate of its previous excess. But 
since the end of January the motion has steadied down 
to its normal degree, and thus we find the period closely 
agreeing with that adopted by Mr. Marth. 
57. November 27 (Dawes). 
V. 1872, February 2, roh. 3 
| (Monthly Notices, vol. xliv. No. 9), based on the period of 
ee Som. 12°25s. The spot must therefore have moved 
28,700 miles to the westward at the rate of 717 miles per 
| terrestrial day, and 294 miles per Jovian day. Then after 
| January 13 it suddenly retrograded if we accept the 
If. IIJ. 1858, March 2, oh. 
12h. som. (Denning). 
The motion of this brilliant white spot prior to 
January 13 is involved in no doubt whatever, so that 
the question of its identity with the one observed 
is an entirely separate one, and cannot 
on January 27 ( 
affect the remarkable phenomena, which the increased 
| velocity exhibited, except as to the retrogressive motion 
