"What then is the office of vitality? We say that it is analogous to that of the engineer who directs the power of the steam-engine in the execution of its work."
"If he had published in 1844, with some fulness, as he then wrought them out," says Professor Gray, "his conception and his attractive illustrations of the sources, transformation, and equivalence of mechanical power, and given them fitting publicity, Henry's name would have been prominent among the pioneers and founders of the modern doctrine of the conservation of energy."
Henry always defined science as the "knowledge of natural law," and law as the "will of God." He found all things, even the storms, under the "control of laws--fixed, immutable, and eternal," and rejoiced in believing that "a Supreme Intelligence who knows no change" governs all. For him there was never any conflict between science and religion.
In February, 1837, Henry went to Europe, accompanied by Prof. Alexander D. Bache, at the head of the United States Coast Survey for eighteen years. He became the friend of Faraday; of Wheatstone, then Professor of Experimental Philosophy in King's College, who was engaged in developing his system of the needle telegraph; of Arago, Gay-Lussac, and other noted men. "At King's College," says Prof. Alfred M. Mayer, "Faraday, Wheatstone, Daniell, and Henry had met to try and evolve the electric spark from the thermopile. Each in turn attempted it and failed. Then came Henry's turn. He succeeded, calling in the aid of his discovery of the effect of a long interpolar wire wrapped around a piece of soft iron. Faraday became as wild as a boy, and, jumping up, shouted: 'Hurrah for the Yankee experiment!'" "It is not generally known or appreciated," says Professor Mayer, "that Henry and Faraday independently discovered the means of producing the electric current and the electric spark from a magnet.... Henry cannot be placed on record as the _first_ discoverer of the magneto-electric current, but it _can_ be claimed that he stands alone as its _second_ independent discoverer." Both James D. Forbes of Edinburgh and Henry obtained the spark, but were anticipated by Faraday.
Henry spoke before the various scientific societies. He was no longer the apprentice to a watch-maker, or the leader of private theatricals, but a distinguished scholar. By his own will and energy he had attained to this enviable position.