234 



SCIENCE 



[N. S. Vol. XXXIII. No. 841 



seven inches and which occurs in great num- 

 bers in the yellow sands around Tuxpam. 



There are also casts of a large variety of 

 other forms of bivalves and gasteropods, and 

 as a whole the fauna is later than that of the 

 San Fernando beds and is probably Miocene. 

 We have called these the Tuxpam beds. 



The evidence now before us indicates that 

 the upper Tertiary deposits mark a gradually 

 sinking coast line along the gulf border in 

 Texas and Mexico which was arrested in the 

 Tampico-Tuxpam region before it was further 

 north. Thus while early Miocene deposits are 

 on the surface almost at the present water's 

 edge at Tampico and have only a small depth 

 of later deposits overlying them, deposits of 

 the upper Miocene are buried 2,300 feet on 

 Galveston Island and are found in drilling at 

 Saratoga seventy miles inland at a depth of 

 over 1,000 feet. j;. T. Dumble 



SOCIETIES AND ACADEMIES 



THE AMERICAN PHILOSOPHICAL SOCIETT 



In an address on modern physics before the 

 American Philosophical Society, recently, Pro- 

 fessor Ernest Fox Nichols, president of Dartmouth 

 College, said in part: 



" i shall try to review very briefly the principal 

 ideas upon which modem physics rests and shall 

 say something about where we think we have 

 arrived in our search for knowledge. I need 

 scarcely remind you that in the natural sciences 

 as in more practical affairs, how we have arrived 

 is as important as where we have arrived. I shall 

 therefore spend some time in presenting detached 

 fragments of the experimental evidence and infer- 

 ences upon which certain conclusions are based, 

 hoping in this way to illustrate some of the con- 

 structive methods of reasoning employed in re- 

 search. 



" The ideas which underlie all our thinking are 

 space, time and inertia or mass. With space and 

 time as a background, the physicist must pursue 

 inertia and everything related to it, along every 

 conceivable path. In this pursuit he comes upon 

 four ultimate though related conceptions: matter, 

 ether, electricity and energy. 



It should be remembered that an important 

 part of our present knowledge of matter, and 

 nearly all tnat we know of ether and electricity, 

 has been gained not immediately but by inference. 



In so many cases we see or know directly only the 

 first and last link of a chain of events and must 

 search by indirect means for the mechanism lying 

 between. 



" At bottom, I suppose, the ether, electricity, 

 force, energy, molecule, atom, electron, are but the 

 symbols of our groping thoughts, created by an 

 inborn necessity of the human mind which strives 

 to make all things reasonable. In this reasoning 

 from things seen and tangible, to things unseen 

 and intangible, the resources of mathematical 

 analysis are applied to the mental images of the 

 investigator, images often suggested to him by his 

 Knowledge of the behavior of material bodies. 

 This process leads first to a working hypothesis, 

 which is then tested in all its conceivable conse- 

 quences, and any phenomena not already known 

 which it requires for its fulfilment, are sought in 

 the laboratory. By this slow advance a working 

 hypothesis which has satisfied all the demands 

 put upon it gradually becomes a theory which 

 steadily gains in authority as more and more new 

 lines of evidence converge upon it and confirm it. 



" As we take up what we believe to be the rela- 

 tions of electricity to matter, we come in places 

 upon slippery ground and the bases of our faith 

 rest on recent foundations. 



" At the outset we encounter one striking differ- 

 ence between electricity and matter. Every free 

 charge of electricity exerts a force upon every 

 other charge in the universe, just as every particle 

 01 matter exerts a force on every other particle of 

 matter, however distant. But with matter the 

 particles are invariably urged toward each other 

 while electric charges may be either drawn to- 

 gether or forced apart depending on the kinds of 

 charges. We have both positive and negative elec- 

 tricity but only one kind of matter. The bald 

 statements of the laws of gravitation and electric 

 force bear a strong resemblance to each other. 

 The laws tell us how the forces vary, but reveal 

 no hint of the machinery by which they act. Of 

 the intimate association of electricity with matter 

 we have learned much from careful study of the 

 processes of electric conduction in solutions and 

 gases." 



The contributions to our knowledge gained 

 from the recent discoveries of cathode rays. X-rays, 

 spectroscopic studies and the amazing properties 

 of radio-active substances were next discussed and 

 in closing Dr. Nichols said: 



" The electron has but a thousandth part of the 

 inertia of the lightest known material atom, and 

 this inertia it doubtless borrows from the kindly 



