demonstration that water exists in the air as an independent
gas--Hutton's theory of rain--Luke Howard's paper
on clouds--Observations on dew, by Professor Wilson and
Mr. Six--Dr. Wells's essay on dew--His observations
on several appearances connected with dew--Isotherms
and ocean currents--Humboldt and the-science of comparative
climatology--His studies of ocean currents--
Maury's theory that gravity is the cause of ocean currents--
Dr. Croll on Climate and Time--Cyclones and anti-cyclones,
--Dove's studies in climatology--Professor Ferrel's
mathematical law of the deflection of winds--Tyndall's estimate
of the amount of heat given off by the liberation of a pound
of vapor--Meteorological observations and weather predictions.

CHAPTER VI. MODERN THEORIES OF HEAT AND LIGHT

Josiah Wedgwood and the clay pyrometer--Count Rumford
and the vibratory theory of heat--His experiments with
boring cannon to determine the nature of heat--Causing
water to boil by the friction of the borer--His final
determination that heat is a form of motion--Thomas Young
and the wave theory of light--His paper on the theory of
light and colors--His exposition of the colors of thin plates--Of
the colors of thick plates, and of striated surfaces, --Arago and
Fresnel champion the wave theory--opposition
to the theory by Biot--The French Academy's tacit
acceptance of the correctness of the theory by its admission of
Fresnel as a member.

CHAPTER VII. THE MODERN DEVELOPMENT OF ELECTRICITY AND MAGNETISM