It was in the Albany Academy that he began that wide series of experiments and investigations which touched so many phases of the great problem of electricity. His first discovery was that a magnet could be immensely strengthened by winding it with insulated wire. He was the first to employ insulated wire wound as on a spool and was able finally to make a magnet which would lift thirty-five hundred pounds. He first showed the difference between "quantity" magnets composed of short lengths of wire connected in parallel, excited by a few large cells, and "intensity" magnets wound with a single long wire and excited by a battery composed of cells in series. This was an original discovery, greatly increasing both the immediate usefulness of the magnet and its possibilities for future experiments. The learned men of Europe, Faraday, Sturgeon, and the rest, were quick to recognize the value of the discoveries of the young Albany schoolmaster. Sturgeon magnanimously said: "Professor Henry has been enabled to produce a magnetic force which totally eclipses every other in the whole annals of magnetism; and no parallel is to be found since the miraculous suspension of the celebrated Oriental imposter in his iron coffin."* * Philosophical Magazine, vol. XI, p. 199 (March, 1832). Henry also discovered the phenomena of self induction and mutual induction. A current sent through a wire in the second story of the building induced currents through a similar wire in the cellar two floors below. In this discovery Henry anticipated Faraday though his results as to mutual induction were not published until he had heard rumors of Faraday's discovery, which he thought to be something different.