During the trip, these messages were received on board the moving train, and each writer had the satisfaction of having his words correctly returned to him. The main feature of the system, that of using the ordinary telegraph wires strung on the poles along the track, in place of a specially laid wire, as in the Phelps system, was invented and patented by Mr. William Wiley Smith in the fall of 1881, and he and Mr. E. T. Gilliland have been associated with Mr. Edison in the development of this idea. The apparatus on board the train is all attached to a compact operator's desk, occupying no more room than an ordinary car seat. This desk may be placed in any part of the car desired, arid may be moved from one car to another in a few minutes' time. The apparatus consists of an ordinary Morse key, phonetic receivers, an electro-magnet, a vibrating reed, an induction coil, and a battery.
Similar apparatus is in use at the fixed stations.
With the assistance of our diagrammatic illustrations, the reader will be able to understand the disposition of the instruments, and follow the current on its journey from the key on the train to the receiver at the fixed station, or vice versa. The car roofs are covered with tin and connected electrically by copper wire. During the experimental run at Staten Island, four cars were used. As the induction takes place between the telegraph wires and the tin roof, it is desirable to have as large a metallic surface as possible. Under favorable conditions, one roof will suffice, but it is better to have several.