354 



SCIENCE. 



[N. S. Vol. XXII. No. 560. 



investigations near the close, when workers 

 (let us be thankful) were many, and the 

 subjects lengthening into detail. Again, 

 the higher order of genius will usually be 

 additionally exalted at the expense of the 

 less gifted thinker. I can but regret that 

 these are the inevitable limitations of the 

 cursory treatment prescribed. As time 

 rolls on the greatest names more and more 

 fully absorb the activity of a whole epoch. 



METROLOGY, 



Finally, it will hardly be possible to con- 

 sider the great advances made in physics 

 except on the theoretical side. Of re- 

 nowned experimental researches, in par- 

 ticular of the investigations of the con- 

 stants of nature to a degree of ever in- 

 creasing accuracy, it is not practicable to 

 give any adequate account. Indeed, the 

 refinement and precision now demanded 

 have placed many subjects beyond the 

 reach of individual experimental research, 

 and have culminated in the establishment 

 of the great national or international labo- 

 ratories of investigation at Sevres (1872), 

 at Berlin (1887, 1890), at London (1900), 

 at Washington (1901). The introduction 

 of uniform international units in cases of 

 the arts and sciences of more recent devel- 

 opment is gradually, but inexorably, urging 

 the same advantages on all. Finally, the 

 access to adequate instruments of research 

 has everywhere become an easier possibility 

 for those duly qualified, and the institu- 

 tions and academies which are systematic- 

 ally undertaking the distribution of the 

 means of reasearch are continually in- 

 creasing in strength and in number. 



CLASSIFICATION. 



In the present paper it will be advisable 

 to follow the usual procedure in physics, 

 taking in order the advances made in 

 dynamics, acoustics, heat, light and elec- 

 tricity. The plan pursued will, there- 

 fore, specifically consider the progress in 



elastics, crystallography, capillarity, solu- 

 tion, diffusion, dynamics, viscosity, hy- 

 drodynamics, acoustics; in thermometry, 

 calorimetry, thermodynamics, kinetic the- 

 ory, thermal radiation; in geometric op- 

 tics, dispersion, photometry, fluorescence, 

 photochemistry, interference, diffraction, 

 polarization, optical media; in electrostat- 

 ics, Volta contacts, Seebeck contacts, elec- 

 trolysis, electric current, magnetism, elec- 

 tromagnetism, electrodynamics, induction, 

 electric oscillation, electric field, radioac- 

 tivity. 



Surely this is too extensive a field for 

 any one man ! Few who are not physicists 

 realize that each of these divisions has a 

 splendid and voluminous history of devel- 

 opment, its own heroes, its sublime classics 

 often culled from the activity of several 

 hundred years. I repeat that few under- 

 stand the unmitigatedly fundamental char- 

 acter, the scope, the vast and profound 

 intellectual possessions, of pure physics; 

 few think of it as the one science into which 

 all other sciences must ultimately converge 

 — or a separate representation would have 

 been given to most of the great divisions 

 which I have named. 



Hence even if the literary references may 

 be given in print with some fullness, it is 

 impossible to refer verbally to more than 

 the chief actors and quite impossible to 

 delineate sharply the real significance and 

 the relations of what has been done. More- 

 over, the dates will in most instances have 

 to be omitted from the reading. It has 

 been my aim, however, to collect the greater 

 papers in the history of physics, and the 

 suggestion is implied that science would 

 gain if by some august tribunal researches 

 of commanding importance were formally 

 canonized for the benefit of posterity. 



ELASTICS. 



To begin with elasticity, whose devel- 

 opment has- been of such marked influ- 



