In line with other efforts to increase the capacity of the wires, the _duplex telegraph_ was invented by Dr. William Gintl, of Austria, in 1853, and was afterwards improved by Carl Frischen, of Hanover, and by Joseph B. Stearns, of Boston, Mass, who in 1872 perfected the duplex (U. S. Pats. No. 126,847, May 14, 1872, and No. 132,933, Nov. 12, 1872). This system doubles the capacity of the telegraphic wire, and its principle of action permits messages sent from the home station to the distant station to have no effect on the home station, but full effect on the distant station, so that the operators at the opposite ends of the line may both telegraph over the same wire, at the same time, in opposite directions. This system has been further enlarged by the quadruplex system of Edison, which was brought out in 1874 (and subsequently developed in U. S. Pat. No. 209,241, Oct. 22, 1878). This enabled four messages to be sent over the same wire at the same time, and is said to have increased the value of the Western Union wires $15,000,000. In 1846 Royal C. House invented the _printing telegraph_, which printed the message automatically on a strip of paper, something after the manner of the typewriter (U. S. Pat. No. 4,464, April 18, 1846). The ingenious mechanism involved in this was somewhat complicated, but its results in printing the message plainly were very satisfactory. This was the prototype of the familiar “_ticker_” of the stock broker’s office, seen in Figs. 10 and 11. In 1856 the Hughes printing telegraph was brought out (U. S. Pat. No. 14,917, May 20, 1856), and in 1858 G. M. Phelps combined the valuable features of the Hughes and House systems (U. S. Pat. No. 26,003, Nov. 1, 1859). [Illustration: FIG. 11.--RECEIVING MESSAGE ON STOCK BROKER’S “TICKER.”] _Fac Simile_ telegraphs constitute another, although less important branch of the art. These accomplished the striking result of reproducing the message at the end of the line in the exact handwriting of the sender, and not only writing, but exact reproductions of all outlines, such as maps, pictures, and so forth, may be sent. The fac simile telegraph originated with F. C. Bakewell, of England, in 1848 (Br. Pat. No. 12,352, of 1848). The Dial Telegraph is still another modification of the telegraph. In this the letters are arranged in a circular series, and a light needle or pointer, concentrically pivoted, is carried back and forth over the letters, and is made to successively point to the desired letters.