Grove from science; for, while it may be possible to find in the ranks of the Bar many who might worthily occupy his place on the Bench, it would be hard to find among men of science any with as wide-reaching and practical philosophy as that which he owns.  The chemist demonstrated long since that it was impossible for man to create or destroy a single particle of ponderable matter; but it remained for our own time to prove that it was equally impossible to create or destroy any of the energy which existed in nature as heat, mechanical power, electricity, or chemical affinity.  All that it is in the power of man to do is to convert one of these forms into another.  This, perhaps the greatest of all scientific discoveries since the time of Newton, was first, I believe, enunciated in 1842 by Grove, in a lecture given at the London Institution; and it was experimentally proved by the researches of Joule, described in a paper which he read at the meeting of the British Association which was held at Cork—­my native city—­in 1843.  My friend Dr. Sullivan, now President of Queen’s College, Cork, and I myself had the privilege of being two of a select audience of half a dozen people, who alone took sufficient interest in the subject to hear for the first time developed the experimental proof of the theory which welds into one coherent system the whole physical forces of the universe, and enables one of these to be measured by another.  One branch of the “correlation of physical forces,” as it was termed by Grove, was the relation between mechanical power and heat, and the convertibility of each into the other, which, under the name of “Thermodynamics,” has become one of the most important branches of practical science.

Joule’s first experiments clearly proved that each of these forms of energy was convertible into the other; but some discrepancies arose in determining the exact equivalent of each.  His subsequent researches, however, clearly demonstrated the true relation between both.  Taking as the unit of heat the amount which would be necessary to raise 1 lb. of water 1 deg. of Fahrenheit’s scale (now called “the English thermal unit"), he proved that this unit was equivalent to the mechanical power which would be required to raise 772 lb. 1 foot, or to raise 1 lb. 772 ft. perpendicularly against the force of gravity.  The heat-unit—­the pound-degree—­which I will distinguish by the Greek letter [theta], is a compound unit of mass and temperature; the second—­the foot-pound = f.p.—­a compound unit of mass and space.  This equation, called “Joule’s equivalent,” or 1 thermal unit = 772 foot-pounds, is the foundation and the corner-stone of thermodynamics.