1896-97.] 
Chairman’s Opening Address. 
171 
in no small degree to the enrichment and social progress of the 
world. Since Lord Kelvin — then William Thomson — became a 
Fellow of this Society, fifty years ago, he has contributed to its 
Proceedings and Transactions , up to 1891, no fewer than seventy- 
two communications, and we reflect with pride on the fact that 
several of his most famous papers were read to this Society. Only 
three of these will I venture to mention on this occasion. The 
Memoirs on Thermo-dynamics, the chief of which appeared in the 
Transactions from 1849 to 1851,* founded on the experimental 
work of Joule, and of Joule and Thomson together, established 
that department of science on a new basis. He was the first to 
investigate methodically and to restate the whole subject from the 
mathematical point of view ; he developed the principles of Carnot 
so as to give the views now current as to the nature of heat ; and 
when he showed how to reckon temperature on an absolute thermo- 
dynamic scale, the dynamical theory of heat secured, its position as a 
recognised branch of physical science. Three years later, in 1852, f 
Thomson announced the principle of the dissipation of energy, and 
showed that a part of the energy of the universe is being slowly 
but surely changed into uniformly diffused heat, and therefore 
ceases to be available for mechanical effect. From this principle 
stupendous consequences flow, and the consideration of these has 
had a marked influence on human thought. Lastly, the papers 
on Yortex Motion, the first of which was read in February 1867, J 
applied our knowledge to the properties of vortex rings, first 
investigated by Helmholtz, towards the conception of an atom. 
Imagining a fluid having only the properties of inertia, invariable 
density, and perfect mobility, the motions of the fluid are submitted 
to mathematical analysis, and on this is founded a theory which may 
not only give a new expression to the atomic theory, but may be 
applied even to gravitation. From these contributions have flowed 
many fruitful results, which no doubt will be recorded by the 
historian of science. 
* W. Thomson, “ On Carnot’s Theory of the Motive Power of Heat,” Trans. 
Roy. Soc. Edin ., 1849 ; “On the Dynamical Theory of Heat,’’ Trans. Roy. 
Soc. Edin., 1851. 
f W. Thomson, “ On a Universal Tendency in Nature to the Dissipation of 
Mechanical Energy,” Proc. Roy. Soc. Edin., 1852. 
+ W. Thomson, “ On Yortex Atoms,” Proc. Roy. Soc. Edin., 1867. 
