Of course he was out of work. He was very fond of the theatre, and, having been behind the scenes, had learned how stage effects are produced. He now joined a private theatrical company, called "The Rostrum," and was soon made president of the society. He dramatized a story, and wrote a comedy, both of which were acted. He seemed destined to become an actor, probably not with the approval of his Scotch Presbyterian mother.
Lives are sometimes changed by seemingly trivial events, yet nothing is trivial that influences a human being. Garfield said, "To every man of great original power there comes, in early youth, a moment of sudden discovery—of self-recognition—when his own nature is revealed to himself, when he catches for the first time a strain of that immortal song to which his own spirit answers, and which becomes thenceforth and forever the inspiration of his life.
"'Like noble music unto noble words.'"
That "moment of sudden discovery" came to Henry at sixteen. A slight accident had confined him to his mother's house for a few days. A young Scotch gentleman, Robert Boyle, who was boarding with her, had left upon the table of his chamber an unostentatious book, "Lectures on Experimental Philosophy, Astronomy, and Chemistry: by G. Gregory, D.D., Vicar of Westham."
The book begins by asking several questions: "You throw a stone, or shoot an arrow into the air; why does it not go forward in the line or direction that you give it? Why does it stop at a certain distance, and then return to you?... On the contrary, why does flame or smoke always mount upward, though no force is used to send them in that direction? And why should not the flame of a candle drop toward the floor when you reverse it, or hold it downward, instead of turning up and ascending into the air?... Again, you look into a clear well of water, and see your own face and figure, as if painted there. Why is this? You are told that it is done by reflection of light. But what is reflection of light?"
Henry took up this book and began to read. Soon it seemed more interesting than Brooke's "Fool of Quality" and all the romances. At the very next meeting of the theatrical society, he resigned the presidency, telling his companions that he should devote his life to solid studies.
Robert Boyle, seeing that the youth was interested in the book, gave it to him. It was ever after preserved in Professor Henry's library, with these words written on the fly-leaf: "This book, although by no means a profound work, has, under Providence, exerted a remarkable influence upon my life. It accidentally fell into my hands when I was about sixteen years old, and was the first work I ever read with attention. It opened to me a new world of thought and enjoyment; invested things before almost unnoticed with the highest interest; fixed my mind on the study of nature, and caused me to resolve, at the time of reading it, that I would immediately commence to devote my life to the acquisition of knowledge."
This resolution was at once put in practice, by attending a night-school, where he soon learned all that the master could teach. His next attempt at education was to learn grammar of a travelling teacher, and so skilled did he become that he made a grammatical tour of the country districts, in imitation of his instructor, earning enough money to enter the Albany Academy. When more money was needed, the enterprising youth found a situation as head of a district school, at eight dollars a month! He pleased his patrons so well that he received fifteen dollars for the second month. Later, he became an assistant in the academy, while still a pupil.
Says Orlando Meads, LL.D.: "When a boy in the Albany Academy in 1823 and 1824, it was my pleasure and privilege, when released from recitations, to resort to the chemical laboratory and lecture room. There might be found from day to day through the winter, earnestly engaged in experiments upon steam and upon a small steam-engine, and in chemical and other scientific investigations, two young men—both active members of the 'Lyceum,' then very different in their external circumstances and prospects in life, but of kindred tastes and sympathies; the one was Richard Varick De Witt, the other was Joseph Henry, as yet unknown to fame, but already giving promise of those rare qualities of mind and character which have since raised him to the very first rank among the experimental philosophers of his time.
"Chemistry at that time was exciting great interest, and Dr. Beck's courses of chemical lectures, conducted every winter in the lecture room of the academy, were attended not only by the students, but by all that was most intelligent and fashionable in the city. Henry ... was then Dr. Beck's chemical assistant, and already an admirable experimentalist, and he availed himself to the utmost of the advantages thus afforded of prosecuting his investigations in chemistry, electricity, and galvanism." Dr. T. Romeyn Beck, the principal, had become interested in the studious young man, and, when he left the academy, recommended him to one of the trustees, General Stephen Van Rensselaer, as a private tutor to his sons. Young Henry's services were engaged, and, as his teaching required but about three hours each day, he devoted his leisure to higher mathematics, in conjunction with chemistry, physiology, and anatomy, as he had decided to become a physician. In his mathematical studies he went so far as to read the Mécanique Analytique of La Grange.