SOME NOTES ON JITPITER DTJRINa HIS OPPOSITION OF 1876. 89 



G-reenwich Observatory states that, with the great equatorial, 

 Jupiter presented appearances not previously recorded, and 

 drawings made from that telescope by Mr, Carpenter coincided 

 entirely with Sir "W. Keith Murray's. The next maximum of 

 1871 I find comparatively bare of records ; but there are accounts 

 scattered here and there among the notices of the E-oyal Astro- 

 nomical Society, of bright spots and patches observed on the 

 equatorial belt ; and if my own negative evidence goes for any- 

 thing, I may state that during this year, which is just after a spot 

 minimum, though I have attentively watched for these phenomena, 

 I cannot record a single sign of them. 



Testimony so far appears to point to a strong probability of 

 the connection of these remarkable features with our eleven-year 

 solar disturbances ; but more is needed before we accept the 

 theory as a fact. If the Earth were viewed from a distance, the 

 auroras most prevalent about the maximum period might give a 

 perceptible tint to parts, but they would be near the poles; 

 there might be similar phenomena producing similar changes on 

 Jupiter. 



The small black spots mentioned in the circular appear to be 

 a class of objects of somewhat more recent observation, and, so 

 far as we can judge from the few observations recorded of them, 

 they seem to coincide with the solar minimum of spots, as the 

 bright spots do with the maximum. They are somewhat minute 

 objects, and might be easily overlooked unless the observer 

 possessed a good glass of large aperture, and an eye used to this 

 particular work ; but granting these conditions — and they become 

 on favourable nights very conspicuous and remarkable pheno- 

 mena — I have at times seen these spots so intensely black that 

 I could scarcely persuade myself that they were not the shadows 

 of satellites crossing the disk of the planet ; but that this is not 

 the truth becomes apparent if we watch them, for they retain 

 their relative position with the other markings, and rotate with 

 them, which of course the shadows of satellites do not do. It 

 is difficult not to believe that these spots have a different 

 nature from the well-known shadings and belts : they are so hard 

 in their outline, and so very much blacker than any of the other 

 markings. It has been I believe suggested that they may be the 

 tops of mountains protruding through the cloudy envelope sur- 

 rounding Jupiter ; but, if this is the case, they must possess 

 extraordinarily feeble powers of reflection, to appear so dark by 

 contrast with their surroundings. 



I have prepared a diagram on a large scale of the disk of 

 Jupiter, which I hope my astronomical friends present will not 

 laugh at. It is not intended to present the appearance repre- 

 sented by Jupiter at any one time, but rather as a map combining 

 some of the more remarkable and persistent features I have 



