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Frmay, Frespruary 23, 1912 
CONTENTS 
The Primary Concepts of Physics: PROFESSOR 
WILLIAM FRANCIS MAGIE ............... 281 
The Movement for Scientific International- 
ism at The Hague: PROFESSOR C.-E. A. 
WYBNSIEON? ccoccoanoopeabodnoeuuoouoUGab 293 
Scientific Notes and News ...............- 296 
University and Educational News .......... 302 
Discussion and Correspondence :— 
The Word Genotype: PRroressor T. D. A. 
COCKERELL; PROFESSOR CHARLES SCHUCHERT 304 
Scientific Books :— 
Young’s Concepts of Algebra and Geom- 
etry, Wilson’s Descriptiwe Geometry, 
Church’s Descriptive Geometry: PROFESSOR 
C. J. Keyser. Traquair’s Les Poissons 
Wealdiens de Bernissartz: Dr. L. Hus- 
SNK codcansovcooapcobvsoadcoonooasbo 304 
The Harris Tidal Machine: SaMvuEL TrER- 
RING dis onctsoceusooncconasooEoodooodS 306 
Special Articles :— 
Xeralsis: H. F. RoBerts. Cryptobranchus 
Alleghaniensis: PROFESSOR Rosert  T. 
BYLOUIN Giavevens ciescid ajc Sueieceratat hereto aero avec 307 
The American Microscopical Society: T. W. 
GAIL OWEASY SY oeeyelevcvet reves ici aves hohe ech alep apexes 309 
The Southern Society for Philosophy and 
PSYCHOLOGY er arsiers suis coiye Wears 309 
The Geological Society of America: Dr. E. 
Os “HOVEY 33.2 ia aeistenereaies eae 310 
MSS. intended for publication and books, etc., intended for 
review should be sent to the Editor of SciENcE, Garrison-on- 
Hudson, N, Y, 
THE PRIMARY CONCEPTS OF PHYSICS1 
THE subject of the present address is one 
that does not often appear on a scientific 
program. Physicists are so busy in en-— 
larging the structure of knowledge that 
few of them concern themselves with the 
consideration of the fundamental concepts 
of the science. Yet it is plainly true that 
if those fundamental or primary concepts 
are not clearly apprehended, or if there is 
doubt as to what they are, the whole struc- 
ture of the science rests on an insecure 
basis. I propose to examine certain ques- 
tions concerning these primary concepts, 
about which there has been and is much 
unsettled opinion. The discussion neces- 
sarily rests upon my own beliefs about 
them. In the nature of the case each man 
can speak positively about them for him- 
self only. It would be very improper to 
dogmatize, and I shall accordingly have to 
erave your pardon for a frequent expres- 
sion of my own opinion, believing it less 
objectionable to be egotistic than to be dog- 
matic. 
The first question which I shall consider 
is that raised by the advocates of the dy- 
namical definition of force, as to the order 
in which the concepts of force and mass 
come in thought when one is constructing 
the science of mechanics, or in other words, 
whether force or mass is the primary con- 
cept. It will be of service in the discus- 
sion if we consider briefly the way in which 
some of the great builders of the science of 
mechanies used these concepts. 
1 Presidential address delivered before the Amer- 
ican Physical Society and Section B of the Amer- 
ican Association for the Advancement of Science, 
at Washington, D. C., December 28, 1911. 
