Henry improved upon this in 1828, but in March of 1829 he exhibited before the Institute a somewhat larger magnet. "A round piece of iron about one-quarter of an inch in diameter was bent into the usual form of a horse-shoe, and, instead of loosely coiling around it a few feet of wire as is usually described, it was tightly wound with thirty-five feet of wire covered with silk, so as to form about four hundred turns; a pair of small galvanic plates, which could be dipped into a tumbler of diluted acid, was soldered to the ends of the wire, and the whole mounted on a stand. With these small plates, the horse-shoe became much more powerfully magnetic than another of the same size and wound in the usual manner, by the application of a battery composed of twenty-eight plates of copper and zinc each eight inches square." "To Henry, therefore," says Mr. Taylor, "belongs the exclusive credit of having first constructed the magnetic 'spool' or 'bobbin,' that form of coil since universally employed for every application of electro-magnetism, of induction, or of magneto-electrics. This was his first great contribution to the science and to the art of galvanic magnetization.... "But, in addition to this large gift to science, Henry has the preëminent claim to popular gratitude of having first practically worked out the differing functions of two entirely different kinds of electro-magnet; the one surrounded with numerous coils of no great length, designated by him the 'quantity' magnet, the other surrounded with a continuous coil of very great length, designated by him the 'intensity' magnet.... Never should it be forgotten that he who first exalted the 'quantity' magnet of Sturgeon from a power of twenty pounds to a power of twenty hundred pounds was the absolute CREATOR of the 'intensity' magnet; and that the principles involved in this creation constitute the indispensable basis of every form of the electro-magnetic telegraph since invented." Professor Silliman of Yale College said: "Henry has the honor of having constructed by far the most powerful magnets that have ever been known; and his last, weighing (armature and all) but 82-1/2 pounds, sustains over a ton;--which is eight times more powerful than any magnet hitherto known in Europe."