In 1877 William E. Sawyer applied for a United States patent for an electric engineering and lighting system, and in January, 1878, entered into a partnership with Albon Man, and the “Sawyer-Man” lamp, see Fig. 51, was produced. In this an incandescent rod of carbon was inclosed in an atmosphere of nitrogen. This marked the beginning of a period of great activity in this field, which finally resulted in the well known form of electric lamp shown in Fig. 52, which was patented by Edison, No. 223,898, January 27, 1880. The distinctive features of this lamp consisted in a bowed filament of carbon of very thin, thread-like character, which was made of paper or carbonized cellulose. This, when sealed in a vacuum, would not burn away, but would give the proper incandescence, and by its small transverse dimension and high resistance to the current, permitted a proper distribution of the electric current to a number of lamps, without a special regulator for each lamp; and which could also be made so cheaply that the lamp could be thrown away when the burner was finally broken. Edison’s claim on this feature of the electric lamp was sharply contested in an interference in the Patent Office by Sawyer and Man, with the decisions alternating first in favor of one and then of the other, but which finally resulted in the grant of a patent to Sawyer and Man, on May 12, 1885. A struggle then began in the courts, which on October 4, 1892, terminated in a decision by the United States Court of Appeals (Edison Electric Light Company vs. United States Lighting Company), awarding the incandescent lamp to Edison. [Illustration: FIG. 51.--SAWYER-MAN LAMP.] [Illustration: FIG. 52.--EDISON’S ELECTRIC LAMP. _A_--Exhausted globe. _B_--Carbon filament. _CC_--Wires sealed in glass. _D_--Line of fusion of two parts of globe. _EF_--Insulating material. _G_--Screw-threads. _HI_--Metal socket. _J_--Fixture arm _K_--Circuit controlling key.] In the early demonstration given by Edison great disturbance was caused in the stock exchanges among the holders of gas shares, as the sensational reportings in the press seemed to indicate that gas was to be superseded entirely. This uneasiness on the London Stock Exchange amounted on October 11, 1878, to a veritable panic, but while the electric light has more than fulfilled the prophecy made for it in many directions, gas shares still continue to be good stocks. [Illustration: FIG. 53.--ELECTRIC LIGHT CIRCUIT.] [Illustration: FIG. 54.--EDISON’S THREE WIRE SYSTEM OF ELECTRIC LIGHT CIRCUITS.]