tenuous as light; yet, in the transformation, this fluid has not lost
its identity. Though unseen, it continues to exist as matter.

_Velocity of Light._

While ever present, light is being incessantly replenished; its action
being instantaneous. The calculations of ROEMER, founded upon
observations made through spaces of 382 and 568 millions of miles of
distance, should not be too confidently accepted, especially as the
results of such conclusions are so vitally important. When we consider
that with our best telescopes directed towards the moon, less than a
quarter of a million of miles distant, nothing really satisfactory may
be discerned, what value, therefore, may be attached to statements
founded upon such thoroughly unreliable data?

BRADLEY'S estimate of the velocity of light, founded upon his study of
"the aberration of light," is even less worthy of consideration.

Any effort to measure such an inconceivable velocity as that claimed for
light, by any means or appliances which may be devised by human
ingenuity, must be regarded as futile. DESCARTES says: "Light reaches us
_instantaneously_ from the sun, and would do so, even if the intervening
distance were greater than that between the earth and heaven."

FOOTNOTES:

[5] Appendix, p. 99.

[B] This term is employed as being most exact and comprehensive, as this
fluid is now known to be the source of all life and all attractions.

CHAPTER V.

SUN-HEAT.

_Its Source and Limits._

Sun-heat is another product of the same retro-action between the sun and
earth; consequently it has the same range and the same boundaries as
when it is viewed as light.

_Tendencies to unsettle in Science._

The scientists of to-day may well look after the soundness of their
favorite theories of the great physical forces; for the uncertain tenure
of old theories, by reason of recent discoveries, is becoming but too
manifest. New phenomena are now observed which require solutions not met
by present hypotheses. The nebular hypothesis which has so long
possessed the scientific mind has, by the discovery of the moons of
Mars, become a thing of the past. According to M. MAICHE, water is found
to be no longer the old-fashioned conventional oxygen and hydrogen, but
essentially a new element must be considered in estimating its
composition.[6]