light or of radiant
heat. A ray of light or a ray of heat is a line perpendicular to the
wave, and in the case here supposed, the rays would be the radii of the
spherical shell." From this it can be seen that a ray of light or heat
corresponds to what is known as the radius vector of a circle (Art. 20),
and therefore a ray of light and heat takes exactly the same path
through space (if we consider the sun as the source of the light and
heat) as the path of the attractive power of Gravitation. Collecting,
therefore, our results from the preceding articles of this chapter, we
learn that heat is due to vibrating wave motion of the Aether, and that
that motion is a motion which is always directed from the central body
which is the source of the heat; and further, that this motion amounts
to a repulsive motion acting in an opposite direction to the attractive
power of gravity or to the centripetal force of Gravitation. What is
more remarkable still, the path of a ray of heat corresponds with, and
takes up exactly the same direction through space, whether it be atomic
space, solar space, or interstellar space, as the attractive force of
Gravitation.

Looking at the subject from the standpoint of the solar system, with the
sun as the central body, we see that while we have the sun, which acts
as the controlling centre of the particular system of planets, holding
all the planets in their orbits by its attractive power, yet at the same
time it is also the source of all light and heat. Now heat being due to
the wave motion of the aetherial medium, such motion being always
exerted from the central body, we arrive at the only legitimate
conclusion that can be arrived at, viz. that the sun is also the source
of a repulsive motion, which motion coincides with the path that the
attractive power of Gravitation takes, that is, along the radius vector
of the circle, as shown in Art. 20.

ART. 66. _Law of Inverse Squares applied to Heat._--The law of inverse
squares which governs not only the Law of Gravitation Attraction (Art.
22), but also electricity and light, is equally applicable to the
phenomena of heat, so that we say the intensity of heat varies inversely
as the square of the distance. Thus, if we double the distance of any
body from the source of heat, the amount of heat which such a body
receives at the increased distance is one-quarter of the heat compared
with its original position. If the distance were trebled, then the