October 28, 1904.] 



SCIENCE. 



555 



globe, a vera caxisa for upheaval will have 

 been found, which may lead tO' further and 

 more detailed conclusions. It should also 

 either elucidate or simplify the subject of 

 the fusion of magmas and their eruptive 

 expulsion. 



The data for constitution and thermal 

 diffusivity will readily be applicable to the 

 problem of the earth's age and will yield 

 a corrected value of the probable lapse of 

 time since the initiation of the consist entior 

 status of the Protogsa. 



The most difficult field in geophysics is 

 the study of solutions at high temperatures. 

 This is largely because both methods and 

 apparatus require to be invented. When 

 work of this kind was undertaken in the 

 laboratory of the Geological Survey, three 

 years since, no furnace existed in which 

 pure anorthite could be melted and a trust- 

 worthy determination of the temi)erat.ure 

 of fusion made. For the study of aqueo- 

 igneous fusion, which must, of course, be 

 performed at considerable pressures, ex- 

 tremely elaborate preparation is necessary ; 

 indeed, all attempts hitherto made in this 

 direction ' have been only very partially 

 successful. 



Were it not that the number of impor- 

 tant rock-forming minerals is small, the 

 study of igneous solutions for geophysical 

 purposes would be an almost hopeless task. 

 The feldspars, the pyroxenes, the amphi- 

 boles and the micas appear to form isomor- 

 phous series and must be studied as such. 

 They, with quartz, make up nearly 93 per 

 cent, of the igneous rocks, nepheline, oliv- 

 ine, leucite, apatite, magnetite and titan- 

 ium minerals substantially completing the 

 list which enter into these rocks in sensible 

 proportions. After the melting points of 

 the minerals have been determined and 

 their isomorphism has been studied, the 

 most important research to be undertaken 

 is that on their eutectic mixtures. Other 



features, however, must receive attention, 

 such as their latent heat, ionization, vis- 

 cosity and diffusivity. Immensely inter- 

 esting will be the study of melts into which 

 hydroxyl enters as a component and which 

 may turn out to be emulsions rather than 

 solutions. Such reseax'ches will constitute 

 a most substantial additiori to physical sci- 

 ence and, as pointed out above, offer a 

 good prospect for the rational classification 

 of rocks. 



Enough has been said to show how 

 closely geophysical researches interlock. 

 Researches at high temperatures must ac- 

 company investigations at common tem- 

 peratures, physics must be supplemented 

 by physical chemistry, mathematical ability 

 of the highest order must be called upon 

 at every step to elucidate difficulties and to 

 draw inferences capable of being again 

 submitted to inquiry, and some geological 

 knowledge, too, is requisite to appreciate 

 the bearing of results and to indicate the 

 questions of importance. No human be- 

 ing has the length of days, the strength, 

 the skill or the knowledge needful to un- 

 dertake, without help, the investigation of 

 geophysics as a whole. Only a few of the 

 topics touched upon in the earlier pages 

 of this essay are independent of coopera- 

 tion; for instance, the astronomical condi- 

 tions favorable to giaeiation and perhaps 

 the application of the mathematics of capil- 

 larity to the problem of erosion. On the 

 other hand, the list of geophysical problems 

 requiring cooperation could be almost in- 

 definitely extended even now, and will be 

 supplemented when the most pressing ques- 

 tions approach their answers. 



Organization increases efficiency in scien- 

 tific woi'k as much as in technical pursuits, 

 though it has seldom been attempted. In- 

 stances in point are the U. S. Geological 

 Survey, the Beichsanstalt and astronomical 

 surveys of the sky. Geophysics, then, is 



