SOME NOTES ON JUPITER DTJRING HIS OPPOSITION OF 1876. 85 



About the beginning of May the following circular from the 

 Eoyal Astronomical Society, London, was handed to me : — 



" E/oyal Astronomical Society, 



Burlington House, London, W., 



March, 1876. 



" The periodicity of changes in the colour and markings upon the planet 

 Jupiter, and the connection that has been suggested between them and the 

 solar phenomena, render it most desirable that a general system of observa- 

 tion of the planet should be organized. To this end. Dr. Lohse, in the year 

 1873, appealed to astronomers in the Northern hemisphere, and a response 

 was made which has enabled him to collect and put on record many valuable 

 descriptions and drawings of the planet's appearance since that time. 



" The Royal Astronomical Society of London is deeply impressed with the 

 importance of the question ; and to assist in carrying out the plan of inter- 

 national observation suggested by Dr. Lohse, it has appointed us as a com- 

 mittee to endeavour to enlist the sympathies of observers generally, so as to 

 obtain as extensive a series of observations as possible. 



" The Southern declination of the planet will for a few years prevent satis- 

 factory results being obtained in Europe, and we therefore desire to appeal to 

 Southern observers to continue the work already begun. 



" Drawings of the planet's appearance should be made as frequently as 

 possible, giving in all cases the local or Grreenwich meantime of the sketch, 

 with particulars of the instrument and power employed, and the state of 

 atmospheric definition. 



" Careful notes of the tints and colours of the belts are most important. 



" Particular attention is requested to the occurrence of the small bright 

 spots, first observed by Mr. Lassell, and to the approximate Jovicentric lati- 

 tudes in which these spots appear ; also to small black spots which are occa- 

 sionally seen in the equatorial zone. 



" The phenomena presented by the satellites in transit, and their varying 

 brightness considered with respect to their orbital position, are matters on 

 which accurate observations are much desired. 



" To ensure uniformity, we beg to send you some forms on which drawings 

 can be made. These have a polar flattening of one-sixteenth. In all cases 

 the north and south poles of the planet should be indicated in the drawing. 



" All drawings and communications should be sent to ' The Secretary of 

 the Jupiter Committee,' Royal Astronomical Society, Burlington House, 

 London, W. 



" Your obedient servants, 



WILLIAM Huaaiisrs. 



E. B. KNOBEL. 

 LINDSAY. 

 OSW. LOHSE. 



A. C. RANYARD. 

 ROSSE. 



F. TERBY. 



T. W. WEBB." 



Having at the time the use of a fine lO^-inch silvered glass 

 reflector, the property of Mr. J. U. C. Colyer, who has for these 

 and other observations kindly placed it at my disposal,! determined 

 immediately on receipt of this circular, to commence and carry 

 out, as far as lay in my power, a systematic course of observations, 

 accompanying them by sketches made at the telescope, and the 

 results up to the present are now before you. In making these 



