92 SOME NOTES ON JUPITER DTJBINa HIS OPPOSITION OP 1876. 



belt, whicli in 1870 was so red that, according to a naked eye 

 observation of Dr. Copeland in September of that year, the general 

 colour of the planet's light was affected by it, shows in nearly all 

 these illustrations very little (if any) colour at all. 



In the year 1874 there appears to have been an increase of 

 colour, for Mr. E. B. Knobel says — " The colours of Jupiter this 

 year have been far more conspicuous than in 1873. A marked 

 change in the tint of the equatorial zone has taken place. In 

 May 1873 it was observed of a decided brick- red tint. On no 

 occasion this year has that tint been remarked, but a bronze yellow 

 or sienna has prevailed for the whole period of observation, though 

 perhaps on one or two nights it approached more to a rich yellow." 



After remaining at a minimum of colour for two or three years, 

 Jupiter seems now to be regaining his tints ; but in many cases 

 I have noticed a marked difference between wbat I now observe 

 and what has been previously recorded. On first directing the 

 telescope to this planet, at the beginning of May last, I was 

 immediately struck with the bright orange-yellow of the equato- 

 rial zone. This was most conspicuous with all powers from 50 to 

 500, and could still be traced with the aperture reduced to 

 4 inches — the colour was of course much affected by bad defini- 

 tion — when the air was unsteady it required almost the full aper- 

 ture to show its existence, and the reduction then required to 

 give a clear perception of the dark streaks would render it almost 

 invisible ; but on a steady night, when a magnifying power of (say) 

 200 could be used with the full aperture, the equatorial zone has 

 appeared almost invariably, with one or two exceptions which I 

 shall mention by-and-by, of a rich orange. Shortly after I com- 

 menced the present series of drawings, I had occasion to show 

 some of them to Mr. H. C. E-ussell, of the Observatory, who was 

 himself engaged in similar observations. The first thing he said 

 when he saw them was — " Why, you don't use the same colours 

 that I do at all." A short time subsequently I went to the 

 Observatory for the sake of comparing the telescopes, and to my 

 utter surprise the equatorial belt that I had invariably observed 

 with the reflector to be a tawny orange or yellow appeared in the 

 ll|--inch refractor of a bright rose-pink. That this was no sudden 

 change in the planet has since been amply confirmed, for Mr. 

 Bussell's drawings and my own on the same nights show each the 

 different colour. Moreover, I have on other occasions compared 

 the glasses, and the same distinction still exists : the reflector 

 continues to show the equatorial belt yellow, and the refractor 

 pink. The same pinkish tint has been observed by me, though in 

 a less degree, on account of the smaller aperture, in a fine 4f -inch 

 refractor, the property of Mr. Alfred Fairfax, of Double Bay. 

 Mr. Russell has recently erected an 11-inch silvered glass reflector 

 of his own manufacture at the Observatory, and he confirms my 



