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.

Meantime a man of science, in England, had thought out a great project for the benefit of his fellow-men. James Smithson, a wealthy English chemist, a Fellow of the Royal Society, unmarried, died in 1829. He left his property, over five hundred and forty thousand dollars, after the death of his nephew, provided that he died childless, "to the United States of America, to found at Washington, under the name of the Smithsonian Institution, an establishment for the increase and diffusion of knowledge among men." The nephew died six years later, unmarried.

This was indeed a wonderful gift,—and from a stranger! Difficulties at once presented themselves. How could the property be used "for the increase and diffusion of knowledge among men"? "For ten years," says Garfield, "Congress wrestled with those nine words of Smithson, and could not handle them. Some political philosophers of that period held that we had no constitutional authority to accept the gift at all, and proposed to send it back to England. Every conceivable proposition was made."

John Quincy Adams desired a great astronomical observatory. One person wished an agricultural school; another, a college for women; another, that the funds should be devoted to meteorological observations all over the Union. Finally, a board of regents was appointed, with power to choose a suitable person as secretary.

He must be a learned man, a wise financier, with good judgment and pleasant manners. Professor Henry fulfilled all the conditions. He was admired for his learning; in finance he was wise, as thirty years have proved, the institute with its endowment now being valued at one and a half million dollars; his kindly manner made him accessible, willing to listen to any one who hoped or believed he had discovered something in the line of knowledge. A man who can be harsh or cold to an ignorant person, or indeed to anybody, does not deserve to hold any public position. With natural quickness of temper in early life, he had gained remarkable self-control. Like Baron Cuvier, he had no tolerance for sarcasm or "practical jokes." Henry was unanimously chosen, entering upon his duties December 3, 1846. He had a definite plan of the work which ought to be done, and "after due deliberation it received the almost unanimous approval of the scientific world."

He believed that the money should be used in original scientific work; by helping men to publish the results of such work; to aid in varied explorations; to send scientific publications all over the world. The institution is now the principal agent of scientific and literary communication between the old world and the new. The number of foreign institutions and correspondents receiving the Smithsonian publications exceeds two thousand, scattered from New Zealand and India to Yokohama, in Japan, and Cape Town, in Southern Africa. The weight of matter sent abroad for ten years, ending 1877, was ninety-nine thousand pounds. Among the first subjects taken up by the institution for investigation was that of American archæology, an attempt to ascertain the industrial, social, and intellectual character of the earliest races on our continent. The first publication of "Smithsonian Contributions" was a work on the mounds and earthworks found in the Mississippi valley, a most fascinating study.

The Smithsonian, "first in the world, organized a comprehensive system of telegraphic meteorology, and has thus given first to Europe and Asia, and now to the United States, that most beneficent national application of modern science—the storm warnings."

So much of value has been gathered by government surveys and by voluntary contribution that the institution has sent duplicates to various societies of specimens in geology, mineralogy, botany, zoölogy, and archæology, while it has remaining, "boxed up, varieties of art and nature" more than enough to twice fill the halls and galleries of the building.

The work of Professor Henry grew more and more onerous, but he seemed to leave nothing undone. For many years he served gratuitously as chairman of the Lighthouse Board. When a substitute was needed for sperm oil, after almost numberless experiments, he showed that lard oil is the best illuminant, thereby saving the country over one hundred thousand dollars yearly, since 1865.