1879 Professor Hughes brought out his beautiful induction balance, and the following year Professor Bell, who had already worked in the same field, consulted him by telegraph as to the best mode of applying the balance to determining the place of the bullet, which had hitherto escaped the probes of the President's physicians. Professor Hughes advised him by telegraph, and with this and other assistance an apparatus was devised which indicated the locality of the ball. A full account of his experiments was given in a paper read before the American Association for the Advancement of Science in August, 1882.
Professor Bell continues to reside in the United States, of which he is a naturalised citizen. He is married to a daughter of Mr. Gardiner G. Hubbard, who in 1860, when she was four years of age, lost her hearing by an illness, but has learned to converse by the Horace-Mann system of watching the lips. Both he and his father-in-law (who had a pecuniary interest in his patents) have made princely fortunes by the introduction of the telephone.