SCIENCE 



Friday, September 13, 1912 



CONTENTS 

 The British Association for the Advancement 

 of Science: — 

 The Nature of Eeat: PROrBssoR H. L. 

 Callendar 321 



The Problem of Mechanical Flight: Pro- 

 PESSOK 6. O. James 336 



Early Man in Smith America 340 



The New Allegheny Observatory 341 



Scientific Notes and News 341 



University and Educational News 344 



Discussion and Correspondence: — - 



A Remedy Worse than the Disease: Dr. 

 Wm. H. Ball 344 



Scientific Boohs: — 



Stanley Sail 's Founders of Modern Psychol- 

 ogy: Professor E. B. Titchener. Cohn- 

 heim on Eneymes : Propessoe Graham Lusk 346 



Special Articles: — 



Symptomatic Development of Cancer: The 

 LATE Dr. W J McGee. Eeversible Changes 

 m Permeability produced by Electrolytes: 

 Professor W. J. V. Osterhout 348 



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

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

 Hudson, N. Y. 



TSE NATUEE OF HEAT^ 



I PROPOSE to consider on the present oc- 

 casion some of our fundamental ideas with 

 regard to the nature of heat, and in par- 

 ticular to suggest that we might with ad- 

 vantage import into our modem theory- 

 some of the ideas of the old calorie or ma- 

 terial theory which has for so long a time 

 been forgotten and discredited. In so 

 doing I may appear to many of you to be 

 taking a retrograde step, because the 

 caloric theory is generally represented as 

 being fundamentally opposed to the kinetic 

 theory and to the law of the conservation 

 of energy. I would, therefore, remark at 

 the outset that this is not necessarily the 

 case, provided that the theory is rightly 

 interpreted and applied in accordance 

 with experiment. Mistakes have been 

 made on both theories, but the method 

 commonly adopted of selecting all the mis- 

 takes made in the application of the caloric 

 theory and contrasting them with the cor- 

 rect deductions from the kinetic theory 

 has created an erroneous impression that 

 there is something fundamentally wrong 

 about the caloric theory, and that it is in 

 the nature of things incapable of correctly 

 representing the facts. I shall endeavor to 

 show that this fictitious antagonism between 

 the two theories is without real foundation. 

 They should rather be regarded as different 

 ways of describing the same phenomena. 

 Neither is complete without the other. 

 The kinetic theory is generally preferable 

 for elementary exposition, and has come to 



' Address of the president to the Mathematical 

 and Physical Science Section of the British Asso- 

 ciation for the Advancement of Science. Dundee, 

 1912. The introductory remarks have been omitted. 



