12 ANNIVERSARY ADDRESS. 
_ From observations made in June last on two bright spots seen 
on Jupiter, Mr. John Brett infers that such spots have a proper 
motion on the surface of the planet, and that they are globular 
bodies almost as large as the earth; and he further infers, from 
their gradual disappearance as they approach the limb, that they 
are wholly immersed in the semi-transparent material of the planet. 
The rate of proper motion assigned to them is 165 miles per hour. 
A most interesting inquiry is opened up by this observation— 
viz., whether there are such bodies revolving about Jupiter. The 
white and black spots so frequently seen, though better defined 
in outline, would seem to belong to some such system. Analogy 
of course would teach us to expect such forms as the results of 
cyclones in the atmosphere of a planet, in consequence of its rota- 
tion. But the rate of motion—165 miles in a hour—is certainly a 
difficulty, as the motion of storm centres on the earth is only 
4 to 6 miles per hour ; but it must not be forgotten that there 
are some barometer waves transmitted through our atmosphere — 
at the rate of 50 miles an hour. 
Professor Hall, of Washington Observatory, using the great 
26-inch refractor, recently detected a small well-defined white 
spot on the planet Saturn. It was reported to six other American 
observatories and carefully watched ; the mean of the observations 
gives a rotation period to the planet of 10 hours 15 minutes, 
which agrees very well with Sir. W. Herschel’s determination, 
made in 1793-4, of 10 hours 16 minutes 0-4 seconds. 
Professor Langley, of Allegheny Observatory, has just pub- 
lished some results of his solar observations, and gives it as_ his 
opinion that the solar atmosphere is proved to be a thin stratum, 
which cuts off one-half of the heat that would otherwise reach 
the garth. This, he considers, is proved by its action in produc- 
ing the dark lines in the spectrum, or, in other words, stopping 
the light and heat of the sun; and he calculates that should this 
envelope be increased 25 per cent. in thickness, the mean tem- 
perature of our globe would be reduced 100° Fahrenheit, and 
possibly some such phenomenon took place in the glacial period. 
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