The first part of my research I communicated to the American Institute of Electrical Engineers in March, 1899. It dealt only with the mathematical theory of my laboratory apparatus. It spoke a great deal about La Grange, but nothing directly about the invention. In October of that year, a friend of mine, Doctor Cary T. Hutchinson, told me that he suspected that an invention was hidden in that communication. “If you have detected it, others have detected it also, and are by this time in the Patent Office,” said I. “Are you not there yourself?” asked Hutchinson, looking somewhat disturbed, and when he heard that I was not he looked discouraged. When, however, I declared my readiness to undertake to design for some clients of his a telephone cable to operate between New York and Boston, guaranteeing to employ a wire not bigger than in ordinary cables capable of operating satisfactorily over a distance of only twenty miles, Hutchinson grew quite serious, and advised me to apply for a patent before doing anything else. I finally followed his advice, and not any too soon. There were others, besides Hutchinson, who had recognized that in my communication to the American Institute of Electrical Engineers there was hidden an invention for which telephone engineers had been eagerly waiting ever since the birth of the telephone art. This created an interference in the Patent Office which annoyed me, but not nearly so much as I had been annoyed there before. About a year from the date of my application for patent, the American Telephone and Telegraph Company acquired my American patent rights, treating me most generously. It gave me what I asked; my friends thought that I had not asked enough, but to a native of Idvor a dollar looks much bigger than to a native of New York who may be a next-door neighbor to some Morgan or Rockefeller. Besides, the opinion of the highest telephone authority in the world that my solution of the extended La Grangian problem had a very important technical value was much more gratifying to me than all the money in the world. In Europe, and particularly in England, the invention came as a surprise; they did not expect an American to make an invention which required so much mathematical analysis of electrical motions, to which the American physicist had contributed very little, whereas Vaschy and Heaviside had written volumes about it. But these writers had paid too little attention to classical writers like La Grange, Thomson, and Kirchhoff. The construction of the inductance-coil required almost as much mathematical analysis as the dynamical theory of the invention, and the method of testing it also was new to the telephone engineers. The coil is now known all over the world as the Pupin coil, and many people think that the coil itself is the invention.