Opinion of the Court
at 68. “In the course of this discussion, it occurred to [Morse] that, by means of electricity, signs representing figures, letters, or words, might be legibly written down at any distance.” Id., at 69. So clear was the idea in Morse’s mind that, “[b]efore he landed in the United States, he had … drawn out in his sketch book … the form of an instrument for an electro-magnetic telegraph.” Ibid.
Immediately upon his arrival in New York, Morse showed his brothers his sketches. See id., at 69–70. He spent the next few years refining his invention. See id., at 70–76. The “great difficulty” he faced was that “the galvanic current, however strong in the beginning, became gradually weaker as it advanced on the wire[,] and was not strong enough to produce a mechanical effect, after a certain distance.” Id., at 107. By 1837, Morse had a solution: “combining two or more electric or galvanic circuits, with independent batteries for the purpose of overcoming the diminished force of electro-magnetism in long circuits.” Id., at 109. Morse demonstrated his telegraph the following year at the Franklin Institute in Philadelphia, and he displayed it soon after in Congress. See id., at 76. He received a patent in 1840, which reissued in 1848. See id., at 81–83.
The litigation that brought Morse before this Court concerned a telegraphic system that Henry O’Reilly had installed between Louisville and Nashville. See id., at 65. Morse sued O’Reilly for infringement, alleging that O’Reilly’s system was “identical with” Morse’s own. Id., at 66. O’Reilly mounted a number of defenses, including that Morse’s patent was void because it lacked an adequate specification. See id., at 99–101, 112.
Morse’s patent included eight claims, and this Court had no trouble upholding seven of them—those limited to the telegraphic structures and systems he had designed. See id., at 85–86, 112, 117. But the Court paused on the eighth. That claim covered “the essence” of the invention, which
