1878. ] : Phystography. 679 
intensely high temperature, all would be found to consist of one 
primitive form of elementary matter. 
One of the most striking results of modern scientific inquiry is 
the discovery, by means of the spectroscope, that there exists in 
the sun’s photosphere some sixteen or seventeen at least of the 
so-called elements, with which we are acquainted on the surface 
of our earth. Herein lies one of those many bonds, by which we 
are connected with our central luminary. The cause of these 
bonds; the origin of sun-heat and earth-heat; and of the sun and 
the earth themselves, now require elucidation. 
According to the now-generally-accepted theory, known as the 
Nebular Hypothesis of Kant and Laplace (and it must be noted 
that we are here passing from the well known to the less known), 
- our solar system was formed from a diffuse nebulous mass. We 
must imagine that this rotating spheroid mass once extended to 
the furthest limits of the solar system, beyond the orbit of 
Neptune. It radiated heat freely into space, and under the force 
of gravitation underwent contraction. And as it contracted it left 
behind it rings of vapor which, breaking up, formed secondary 
rotating spheroids, themselves contracting, themselves leaving be- 
hind them rings, forming tertiary spheroids, themselves passing in 
their orbits round the central mass. That central spheroid mass 
is the sun; one of the secondary rotating spheroids is the earth, 
the moon being a tertiary spheroid. The earth-planet thus formed 
was gaseous; but as time rolled on, it passed through the liquid 
state, to the more or less solid state, which it at present possesses. 
Sun-heat is therefore the result of the condensation of the 
primary spheroid: earth-heat the remnant of that produced by 
the condensation of a secondary nebulous spheroid. 
And now comes the question, how was the rotating nebulous 
spheroid formed? 
If we take a small piece of lead and deal it a number of heavy 
blows with a hammer, we shall find that the lead becomes hot. 
If we continue to hammer for ten minutes, we shall find that the 
lead becomes too hot to hold. Now what is the cause of the 
heating of the lead. Simply this: when the lead is struck, the 
motion of the hammer is suddenly stopped; but the motion is 
taken up in a new form by the particles of the lead, and this new 
form of motion is heat. The visible motion of the hammer is 
converted into the invisible molecular motion of heat; for heat is- 
simply the rapid vibration of the ultimate particles of matter. 
