SCIENCE 



A WEEKLY JOURNAL DEVOTES TO THE ADVANCEMENT OF SCIENCE, PUBLISHING THE 



OFFICIAL NOTICES AND PROCEEDINGS OF THE AMERICAN ASSOCIATION 



FOR THE ADVANCEMENT OF SCIENCE. 



Feiday, Febeuaey 5, 1909 

 contents 



The AmeriooM, Association for the Advance- 

 ment of Science: — 

 The Study of Igneous Rocks: Peofessoe 

 Joseph i*. Iddings 201 



The Conduct of Scientific Work under the 

 United States Government 217 



Recent Work of the Mount Wilson Solar Ob- 

 servatory : De. Geo. E. Hale 220 



The Brooks Memorial 222 



Scientific Notes and News 223 



University and Educational News 227 



Discussion and Correspondence: — 



The Law of Radiation: Dr. J. M. Schae- 

 BERLE. AmericoAi Scientific Productivity: 

 Peofessoe J. McKeen Cattell 227 



Scientific Books: — 

 Bottger's Qualitative AiMlyse : Professor 

 E. Renoup. Schorlemmer's Chemistry: 

 Professor Henry Fat. Lead and Zinc in 

 the United States : Dr. H. 0. Hofman . . . 229 



Scientific Journals and Articles 232 



Botanical Notes: — ■ 



Physiology and Ecology; Economic Botany : 

 Professor Chakles E. Bessey 232 



Special Articles: — 



Sex Determination and Parthenogenesis in 

 Phylloxerans and Aphids: Professor T. H. 

 Morgan. Momentum Effects in Electric 

 Discharge: Professor Francis E. Nipheb 234 



Societies and Academies: — ■ 



The Anthropological Society of Washing- 

 ton: Dr. Walter Hough. The Geological 

 Society of Washington: Dr. Ralph Arnold. 

 The Chemical Society of Washington : J. A. 

 LeClerc 238 



MSS. intended for publication and books, etc., intended for 

 review should be sent to the Editor of Science, Garrison-on- 

 Hudson, N, Y. 



THE AMERICAN ASSOCIATION FOB THE 



ADVANCEMENT OF SCIENCE 



THE STUDY OF IGNEOUS ROCKS'^ 



No branch of petrology presents so at- 

 tractive a field for investigation and study 

 as that concerned with the origin and for- 

 mation of igneous rocks. The great prob- 

 lems of metamorphism that traverse so 

 much of the earth's dynamic history and 

 involve so many factors common to the 

 problems of igneous rocks are less alluring 

 because of their greater complexity, and 

 less definite character. While much is 

 being done in each of these fields of rock 

 study, it is to the former that I wish to call 

 attention at this time. It is interesting to 

 note how the attitude of the petrographer 

 toward the subject of igneous rocks has 

 changed with increasing knowledge of 

 their composition, and with advancing ex- 

 perience with the fundamental laws of 

 physics and chemistry. 



Rocks that were considered igneous a cen- 

 tury ago were almost wholly those known 

 to have poured forth from volcanic craters, 

 and were, for the most part, compact, 

 aphanitic lavas, often containing porphy- 

 ritic crystals — distinctly volcanic rocks. 

 The great number of phanerocrystalline 

 massive rocks were not generally considered 

 as having the same character and origin as 

 volcanic rocks, as being igneous. Their 

 formation was explained in different ways 

 by various geologists. And when treated 



' Address of the vice-president and chairman of 

 Section E — Geology and Geography — American 

 Association for t .e Advancement of Science, Balti- 

 more, 1908. 



