The ever-shifting ground of scientific progress, p. 203--Solar and telluric problems, p. 205--Mayer's explanation of the continued heat of the sun, p. 206--Helmholtz's suggestion as to the explanation, p. 207--The estimate of the heat-giving life of the sun by Lord Kelvin and Professor Tait, p. 208--Lockyer's suggestion that the chemical combination of elements might account for the sun's heat, p. 209--Computations as to the age of the earth's crust, p. 210--Lord Kelvin's computation of the rigidity of the telluric structure, p. 211--Estimates of the future life of the earth, p. 212--Physical problems, p. 213--Attempts to explain the power of gravitation, p. 214--The theory of Le Sage, p. 214--Speculations based upon the hypothesis of the vortex atom, p. 216--Lord Kelvin's estimate of the vortex theory, p. 217--Attempted explanation of the affinity of atoms, p. 217--Solubility, as explained by Ostwald and Mendeleef, p. 218--Professor Van 't Hoof's studies of the space relations of atoms, p. 219--Life problems, p. 220--Question as to living forms on other worlds besides our own, p. 21 x--The question of the "spontaneous generation" of living protoplasm, p. 222--The question of the evolution from non-vital to vital matter, p. 223--The possibility of producing organic matter from inorganic in the laboratory, p. 224--Questions as to the structure of the cell, p. 225--Van Beneden's discovery of the centrosome, p. 226--Some problems of anthropology, p. 227. CHAPTER IX--RETROSPECT AND PROSPECT The scientific attitude of mind, p. 2 30--Natural versus supernatural, p. 233--Inductive versus deductive reasoning, p. 235--Logical induction versus hasty generalization, p. 239--The future of Darwinism, p. 241. APPENDIX A LIST OF SOURCES A HISTORY OF SCIENCE--BOOK V ASPECTS OF RECENT SCIENCE STUDENTS of the classics will recall that the old Roman historians were accustomed to detail the events of the remote past in what they were pleased to call annals, and to elaborate contemporary events into so-called histories. Actuated perhaps by the same motives, though with no conscious thought of imitation, I have been led to conclude this history of the development of natural science with a few chapters somewhat different in scope and in manner from the ones that have gone before.