ANNIVERSARY ADDRESS. 25 



that an atom is a vortex ring of ether, in ether. The theory of 

 the motion of viscous fluids has so far however, been scarcely- 

 attacked. 



The study of the circulation of the atmosphere was greatly 

 advanced by William Ferrel [1817-1891], who, according to the 

 dictum of Hann of Vienna, has contributed more to the know- 

 ledge of the physics of the atmosphere than any other meteorologist. 



In electricity and magnetism, Cavendish [1731 - 1810], Coulomb 

 [1736 - 1806], Ampere [1775 - 1836], Gauss and Wilhelm Weber 

 [1804- 1891] established systems of measurement, which made it 

 possible to study these subjects quantitatively. The equation of 

 Laplace modified by Poisson, was applied by Green [1793 — 1841] 

 to the theory of electricity and magnetism, with significant results. 

 W. Thomson's prediction of the oscillatory nature of the Leyden 

 jar discharge, Lamb's and Niven's investigations of the screening 

 effects of metal sheets against induction, Kirchhoff's [1824 - 1887] 

 determinations of current strength under different circumstances, 

 Maxwell's [1831 - 1879] electro-magnetic theory of light, after- 

 wards experimentally verified by Hertz, and developed by Strutt 

 (Lord Rayleigh), J. J. Thomson, Rowland, Glazebrook, Helmholtz, 

 Boltzmann, Heaviside, Poynting and others, are some of the great 

 advances in one department of physics. 



In the theory of energy, Mayer [1814- 1878], Colding, Joule 

 [1818- 1889], and Helmholtz, established the doctrine of conser- 

 vation, Joule determining also the mechanical equivalent of heat. 

 In 1824 Sadi-Carnot [1796-1832] evolved the theory of heat- 

 engines. In February 1850, Clausius [1822-1888] published 

 the second law of thermodynamics, and illustrated its physical 

 significance, as also did W. J. M. Rankine [1820 — 1872] though 

 he did not then explicitly state the law. The application of the 

 thermodynamic method has completely transformed molecular 

 physics and theoretical chemistry. In respect of this last Dulk 

 has lately made an attempt, apparently, 1 to deduce atomic weights 



1 Atom ere wicht oder Atomgravitation. — Breslau 1898. [I have not seen 

 the work.] 



