XV—NOTES ON THE PHYSICAL APPEARANCE OF THE PLANET 
JUPITER DURING THE SEASON 1880-1. accompantep sy SkKercues 
MADE AT THE OBSERVATORY, Brrr Castie, By Dr. Orro Borppicknr.—Pr ath XV. 
[Communicated by the Earl of Rosse.—Received July 6th, 1881.] 
[Read November 21st, 1881. ] 
During the past winter pencil sketches of the planet Jupiter were made at the 
Observatory, Birr Castle, as often as weather permitted, and out of them a selection 
of twenty-five was made for publication. The drawings were executed by Dr. Otto 
Boeddicker, and have been reduced in the proportion of 24 to 1, by the Woodbury 
type process for the accompanying plate. 
The Reflector of three feet aperture was on every occasion employed. The 
speculum was in fair order, having a good figure, but, having been in use for a year 
or more, since repolishing, it had lost some of its original brightness. 
It is hoped, though iess advantage can be expected from the larger aperture when 
used upon so bright an object as a planet than is the case with the nebule, that at 
least the drawings may prove useful in filling up gaps in series executed by other 
observers. 
The following notes were made during the observations. 
Rosse. 
Power. Usually 144, in some cases 216. 
Time. The time given is the mean Greenwich time of the commencement of 
a drawing. The drawing was finished during 10m. on the average ; the first part 
marked down being the most prominent feature of the planet’s surface, for instance, 
where the red spot was at all visible, its position. 
The drawings are arranged in order of longitude of the planet’s central me- 
ridian, taken from Marth’s Ephemeries in “ Monthly Notices,” No. 7, May, 1880. 
TRANS, ROY. DUB. SOC, N.S. VOL. I- 2 Pe 
