90 SOME NOTES ON JUPITER DUEING HIS OPPOSITION OP 1876. 



observed on his disk. I hope by its aid to make some of my 

 remarks more intelligible, and have purposely exaggerated both 

 colours and markings, in order that they may at a distance make 

 themselves more readil}^ seen. The black spots, you will observe, 

 make their appearance principall}'" on the darker bands ; in fact, 

 I have only recorded one occasion on which I noticed a black 

 spot on the brighter portion of the planet, but that was a very 

 remarkable one ; it was quite as black as the shadow of 'No. 1 

 satellite, and was connected with the equatorial belt by a thin 

 ligament. The next thing I would direct your attention to is 

 the colour of the various portions of the disk ; and here we open 

 Pandora's box of trouble ; for different eyes, different telescopes, 

 and different states of our atmosphere, combine to give most 

 conflicting statements. There is matter enough in this portion 

 of my subject to form a treatise by itself, but time will not permit 

 me to do more than give a brief statement of facts, and leave 

 theorizing on the matter for some other occasion. I would, 

 however, first give you a short account of what I have been able 

 to find recorded of previous observations of the colours of Jupiter, 

 in order that you may compare them with my own, as illustrated 

 in the drawings before you. 



Sir "William Herschel, in " The Philosophical Transactions, 

 1794," says — "I viewed Jupiter with a 40-feet reflector. There are 

 two very dark, broad belts, divided by an equatorial zone or space, 

 the colour of which is of a yellow cast." To take more recent 

 observations, I note that on 7th November, 1869, Mr. T. Elger, 

 of Bedford, says — " I noticed the space between tlie central belts 

 was peculiarly ruddy." Mr. Salter, of Manchester, says, on the 

 same date — " The colour of the equatorial streak was rich tawny." 

 Mr. Gledhill, E.R.S., same date, says — " Whenever the air was 

 good the ruddy tinge of the equatorial belt was easily seen." A 

 photograph of the planet taken in this year shows the equatorial 

 belt absolutely transparent, the light from the ruddy belt having 

 failed to act upon the sensitive plate; yet, speaking of this par- 

 ticular photograph, Mr. Browning says, he has seen photographs 

 taken at other times when this belt exerted the most action. In 

 the year 1871 Mr, John Browning devoted some attention to the 

 planet, and his drawings show the equatorial belt to be of a bright 

 yellow colour. Towards the end of 1871 there appears from 

 various records to have been a general diminution in the intensity 

 of the colours, and more especially in that of the equatorial belt, 

 which had lost much of its yellowish hue. In 1872 Mr. Birmingham 

 describes the equatorial belt as rose-coloured. In the same year 

 Mr, Browning again draws the planet, and his views show a red- 

 dish yellow. The colour generally of the planet in this year, from 

 various records, seems to have been particularly vivid, and Mr. 

 Lassell a.'Dpears especially titruck with it, 1 will quote his 



