Ii8 The Amencan Geologist. August, i899 
heat dominates its surface temperatures and expands the 
greater portion of the water within the sphere of its control 
into an enveloping spherical shell. 
i^Note.) [There are certain phenomena observed on the 
planet Jupiter which indicate that it is now in a condition 
somewhat similar to the above conceived condition of the 
earth, when its cosmic existence merged into its geological 
life. So far as our knowledge of Jupiter now extends that, 
planet appears to be a mass of unknown size shrouded in a 
densely clouded atmosphere. The surface of this cloud 
sphere is marked by a series of bands and spots ranged in 
zonc.^ parallel with the equator. Another notable feature is 
the "great red spot," situated in south equatorial latitude and 
extending through nearly one-eleventh of the circumference 
of the planet. The spots in the bands adjacent to the "red 
spot" have velocities greater than that of the "red spot," and 
in a period of about 45 days make no revolutions whilst the 
"red spot" makes 109. In approaching and passing it from 
the west they are pushed aside and regain their former posi- 
tion further east. Spots in equatorial regions revolve faster 
than spots in temperate latitudes. 
These and other observed phenomena seem to indicate that 
the velocities of these spots are probably accelerated by solar 
energy and that the greater portion of the solar energy reach- 
ing Jupiter is absorbed in its atmosphere. Jupiter receives 
less than 4 per cent, of the heat received by an equal unit of 
area upon the earth. It is doubtful whether this amount of 
heat could keep up sufficient evaporation to shroud the planet 
in clouds. The existence of a cloud sphere about the planet 
therefore, indicates the presence of a considerable amount of 
internal heat. This great planet appears to be in a condi- 
tion which the earth has probably passed through in its cli- 
matic development — merely a heated mass enshrouded in a 
densely clouded atmosphere, through which heat passes prin- 
cipally in the latent form of maintaining water in vaporous 
condition.] 
Now, after admitting that, at any time in the past, internal 
heal has controlled surface temperatures, we should be care- 
ful not to rule it out without reason. The fact that it was 
originallv one of the two known sources of heat, and that 
