HENRY, JOSEPH - HENRY'S ALBANY MAGNET.

On the application of the principle of the galvanic multiplier to electromagnetic apparatus, and also to the development of great magnetic power in soft Iron, with a small galvanic element.

New Haven, Hezekiah Howe and A.H. Maltby, 1831. 8vo. Contemp. hcalf. Spine gilt, tome-and titlelabels with gilt lettering. Light wear along edgaes and top of spine. In: "The American Journal of Science and Arts. Conducted by Benjamin Silliman", Vol. XIX. Engraved frontispiece. VIII,404 pp., 4 engraved plates (1 handcoloured, brownspotted). Henry's paper: pp. 400-408, one textillustr.

First edition of Henry's importent paper in which he described the function and construction of the Albany-Magnet, probably the most powerfull magnet ever constructed (at the time).

From his "experiments Henry discovered that if a cell of a single pair of electrodes is to be used with a given magnet, the magnet should be wound with several coils of wire in parallel; on the other hand, if a battery of many cells is to be used, the magnet winding should form a single long wire. Henry was the first person to understand this idea. It later became a fundamental basis for much of electrical technology, and, in particular, made Samuel F. B. Morse's telegraph feasible.
Applying this principle (together with the valuable but less easily described practical skill in magnet-making he had acquired in the course of his experiments), Henry, with the assistance of a colleague, Philip Ten Eyck, went on to build a 21-pound "experimental magnet on a large scale." With a modest battery, this "Albany magnet" supported 750 pounds, making it, Henry claimed, "probably, therefore, the most powerful magnet ever constructed." Quickly he wrote a paper describing these experiments and his magnet-winding principle, and sent it off to Benjamin Silliman, Professor of Chemistry and Natural History at Yale College and editor of the American Journal of Science, a widely read and influential publication. Silliman readily accepted what he called Henry's "highly important & interesting paper" and published it in the issue of January, 1831 (the paper offered)." (Roger Sherman).

Order-nr.: 47029