LXXI
The undulatory theory (supported by Huyghens and Euler)
does not only explain all these phenomena, it shows also a won
derful connection and harmony with the analogous vibrations of
fluids, sound, heat a. s. o. 354. Not only utility but also beauty,
harmony and aesthetic effects belong to the purposes of creation!
It seems the oscillatory vibrations of the ether appear according
to different modifications as light or heat or electricity. The
subtility of this ether seems to be beyond all comprehension.
Babinet has calculated, that the subtility of the luminiferous
ether of comets in comparison with our atmospheric air corres
ponds to a fraction, the numerator of which is = 1 and the deno
minator 10125, hence a number consisting of 126 ciphers.
§ 176. The various sources of light are: The sun, stars,
heat, chemical combinations (putrefaction, f. e. in decaying
wood), electricity, phosphorescence. 355. Any condensation or
agitation of matter, be it caused by mechanical pressure or
by an electric stream or by attraction of the molecules in
consequence of chemical combinations or by the contact of fine
distributed substances etc., may under favorable circumstances
disengage heat and light. As to chemical combinations a piece
of chlorate of potash thrown into spirit of wine and
touched by a drop of sulphuric acid, the decomposition of the
potash will cause the spirit of wine to burn with a bright flame.
There are some substances, which emit light on account of their
affinity to the oxygen of the air; they are called Pyrophorus
(Phosphorus, fulminating mercury, the dangerous product of a
decomposition of spirit of wine with mercury). Some vege
tables, animals and decaying wood show a spontaneous phos
phorescence. Some bodies have the remarkable property to
absorb light and to continue the vibrations of the ether for some
time in their inside. Fluorspar shines for weeks after it has been
