Note 15 — A General Comparison of the Demonstration with the Facts of Geology.
Reading edition
The truth of this fact is easily established by either observation or experiment. At the close of a hot day should a slight cloudiness supervene, the loss of heat by radiation from the surface is checked; the air at the surface, and the surface, remain at the same temperature, and nature’s delicate differential thermometer—the deposition or non-deposition of dew—records the non-transcalency of clouds, in terms worthy of consideration.
Again, let two delicate thermometers be exposed, one to the air temperature and the other in addition to direct solar rays; the latter will mark the increased temperature due to such exposure. Upon the intervention of a cloud, or even a jet of steam, both instruments will mark the same temperature.
See Physical Geography of the Sea. Maury, 6th ed., p. 212, et seq. Climate and Time, Croll, p. 60, et seq. Climate and Cosmology, Croll, p. 51.