Produced by Charles Keller A HISTORY OF SCIENCE MODERN DEVELOPMENT OF THE PHYSICAL SCIENCES By Henry Smith Williams, M.D., Ll.D. Assisted By Edward H. Williams, M.D. In Five Volumes Volume III. CONTENTS BOOK III CHAPTER I. THE SUCCESSORS OF NEWTON IN ASTRONOMY The work of Johannes Hevelius--Halley and Hevelius--Halley's observation of the transit of Mercury, and his method of determining the parallax of the planets--Halley's observation of meteors--His inability to explain these bodies--The important work of James Bradley--Lacaille's measurement of the arc of the meridian--The determination of the question as to the exact shape of the earth--D'Alembert and his influence upon science--Delambre's History of Astronomy--The astronomical work of Euler. CHAPTER II. THE PROGRESS OF MODERN ASTRONOMY The work of William Herschel--His discovery of Uranus--His discovery that the stars are suns--His conception of the universe--His deduction that gravitation has caused the grouping of the heavenly bodies--The nebula, hypothesis,--Immanuel Kant's conception of the formation of the world--Defects in Kant's conception--Laplace's final solution of the problem--His explanation in detail--Change in the mental attitude of the world since Bruno--Asteroids and satellites--Discoveries of Olbersl--The mathematical calculations of Adams and Leverrier--The discovery of the inner ring of Saturn--Clerk Maxwell's paper on the stability of Saturn's rings--Helmholtz's conception of the action of tidal friction--Professor G. H. Darwin's estimate of the consequences of tidal action--Comets and meteors--Bredichin's cometary theory--The final solution of the structure of comets--Newcomb's estimate of the amount of cometary dust swept up daily by the earth--The fixed stars--John Herschel's studies of double stars--Fraunhofer's perfection of the refracting telescope--Bessel's measurement of the parallax of a star,--Henderson's measurements--Kirchhoff and Bunsen's perfection of the spectroscope--Wonderful revelations of the spectroscope--Lord Kelvin's estimate of the time that will be required for the earth to become completely cooled--Alvan Clark's discovery of the companion star of Sirius--The advent of the photographic film in astronomy--Dr. Huggins's studies of nebulae--Sir Norman Lockyer's "cosmogonic guess,"--Croll's pre-nebular theory. CHAPTER III. THE NEW SCIENCE OF PALEONTOLOGY