his pupil Faraday. There is, then, an
intangible but none the less potent web of association between the
scientific work of Rumford and some of the most important researches
that were conducted at the Royal Institution long years after his death;
and one is led to feel that it was not merely a coincidence that some
of Faraday's most important labors should have served to place on a firm
footing the thesis for which Rumford battled; and that Tyndall should
have been the first in his "beautiful book" called _Heat, a Mode of
Motion_, to give wide popular announcement to the fact that at last the
scientific world had accepted the proposition which Rumford had vainly
demonstrated three-quarters of a century before.

This same web of association extends just as clearly to the most
important work which has been done at the Royal Institution in the
present generation, and which is still being prosecuted there--the
work, namely, of Professor James Dewar on the properties of matter at
excessively low temperatures. Indeed, this work is in the clearest sense
a direct continuation of researches which Davy and Faraday inaugurated
in 1823 and which Faraday continued in 1844. In the former year Faraday,
acting on a suggestion of Davy's, performed an experiment which resulted
in the production of a "clear yellow oil" which was presently proved to
be liquid chlorine. Now chlorine, in its pure state, had previously been
known (except in a forgotten experiment of Northmore's) only as a gas.
Its transmutation into liquid form was therefore regarded as a very
startling phenomenon. But the clew thus gained, other gases were
subjected to similar conditions by Davy, and particularly by Faraday,
with the result that several of them, including sulphurous, carbonic,
and hydrochloric acids were liquefied. The method employed, stated in
familiar terms, was the application of cold and of pressure. The results
went far towards justifying an extraordinary prediction made by that
extraordinary man, John Dalton, as long ago as 1801, to the effect that
by sufficient cooling and compressing all gases might be transformed
into liquids--a conclusion to which Dalton had vaulted, with the
sureness of supreme genius, from his famous studies of the properties of
aqueous vapor.

Between Dalton's theoretical conclusion, however, and experimental
demonstration there was a tremendous gap, which the means at the
disposal of the scientific world in 1823 did not enabl