me that.” Jaime had made mention of the Free Cities,

CHAPTER IV. THE ORIGIN AND DEVELOPMENT OF MODERN GEOLOGY

James Hutton and the study of the rocks--His theory of the earth--His belief in volcanic cataclysms in raising and forming the continents--His famous paper before the Royal Society of Edinburgh, 1781---His conclusions that all strata of the earth have their origin at the bottom of the sea---His deduction that heated and expanded matter caused the elevation of land above the sea-level--Indifference at first shown this remarkable paper--Neptunists versus Plutonists-- Scrope's classical work on volcanoes--Final acceptance of Hutton's explanation of the origin of granites--Lyell and uniformitarianism--Observations on the gradual elevation of the coast-lines of Sweden and Patagonia--Observations on the enormous amount of land erosion constantly taking place, --Agassiz and the glacial theory--Perraudin the chamois- hunter, and his explanation of perched bowlders--De Charpentier's acceptance of Perraudin's explanation--Agassiz's paper on his Alpine studies--His conclusion that the Alps were once covered with an ice-sheet--Final acceptance of the glacial theory--The geological ages--The work of Murchison and Sedgwick--Formation of the American continents--Past, present, and future.

CHAPTER V. THE NEW SCIENCE OF METEOROLOGY

Biot's investigations of meteors--The observations of Brandes and Benzenberg on the velocity of falling stars-- Professor Olmstead's observations on the meteoric shower of 1833- -Confirmation of Chladni's hypothesis of 1794--The aurora borealis--Franklin's suggestion that it is of electrical origin--Its close association with terrestrial magnetism--Evaporation, cloud-formation, and dew--Dalton's 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

Galvani and the beginning of modern electricity--The construction of the voltaic pile--Nicholson's and Carlisle's discovery that the galvanic current decomposes water--Decomposition of various substances by Sir Humphry Davy--His construction of an arc-light--The deflection of the magnetic needle by electricity demonstrated by Oersted--Effect of this important discovery--Ampere creates the science of electro-dynamics--Joseph Henry's studies of electromagnets--Michael Faraday begins his studies of electromagnetic induction--His famous paper before the Royal Society, in 1831, in which he demonstrates electro-magnetic induction--His explanation of Arago's rotating disk--The search for a satisfactory method of storing electricity-- Roentgen rays, or X-rays.