OBSERVATIONS ON JUPITER IN 1870-71. 
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largest dimensions, appears from the very curious object deli- 
neated by Mayer and Grledhill ; while some older drawings by 
one of our first observers, which I have been permitted to see, 
prove that they have been in other seasons abundantly developed 
in less central latitudes. At present we seem far from any 
solution of this mystery, while so little of a similar character 
can be traced among the cloud-masses of our own skies. 
It may be worth consideration whether the superior bright- 
ness of the interior of the disc might lead to any inference as 
to the nature of the reflecting material. It is well known that 
fihe difference, though not perceptible by the eye, is very 
material, as we can in no other way explain the singular change 
occasionally noticed in some of the satellites to chocolate-colour 
or even absolute blackness during the time of transit. It 
would be interesting to know whether this very remarkable 
effect of contrast has ever taken place in front of the dark belts ; 
more probably it has been confined to the luminous zones. 
Experiments might perhaps be devised which might show 
whether the more compact and regularly rounded of our white 
terrestrial cumuli exhibit any similar inequalities of luminosity, 
dependent on the angles of illumination and reflection. Many 
points of interest may probably be elucidated by other means 
than direct telescopic vision ; and we must look forward with 
especial interest to the results which are, we trust, reserved for 
the magnificent apparatus and experienced eye of Dr. Huggins. 
A comparison of the sketches taken by myself during the 
years 1869, 1870, and 1871, with the exquisite views of Dawes 
in 1857 (‘Monthly Notices of R. A. S.,’ xviii. 8, 50, 72), pre- 
sents so much similarity in various respects, as to lead to a curious 
suspicion that the whole atmospheric shell of the planet, with- 
out any material disturbance in its relative arrangements, may 
have been shifted Southward by more than half the breadth of the 
equatorial zone ; the South torrid belt, identified by its attendant 
festoons, occupying at that time a position very near the centre 
of the disc ; while several of the characteristic features of what 
we have termed the South temperate zone and belt are to be 
recognised in a corresponding position of greater remoteness 
from the Pole. So lively was the first impression of this that 
I thought it might have been at once accounted for by a re- 
versed presentation of the planet’s axis ; but on considering 
the dates, as well as the position of a satellite sketched by 
Dawes in transit, I found that no such explanation could be 
admitted. However little weight may be due to such a com- 
parison, it suggests, at any rate, the desirableness of micro- 
metric measurements of the latitude of the principal belts 
during future oppositions. 
