Miscellaneous Inventions - 2

Miscellaneous Inventions - 2

 It is hard to determine where to begin with Edison's miscellaneous inventions, but

perhaps telegraphy has the "right of line," and Edison's work in that field puts him abreast

of the latest wireless developments that fill the world with wonder. "I perfected a system

of train telegraphy between stations and trains in motion whereby messages could be sent

from the moving train to the central office; and this was the forerunner of wireless

telegraphy. This system was used for a number of years on the Lehigh Valley Railroad on

their construction trains. The electric wave passed from a piece of metal on top of the car

across the air to the telegraph wires; and then proceeded to the despatcher's office. In my

first experiments with this system I tried it on the Staten Island Railroad, and employed

an operator named King to do the experimenting. He reported results every day, and

received instructions by mail; but for some reason he could send messages all right when

the train went in one direction, but could not make it go in the contrary direction. I made

suggestions of every kind to get around this phenomenon. Finally I telegraphed King to

find out if he had any suggestions himself; and I received a reply that the only way he

could propose to get around the difficulty was to put the island on a pivot so it could be

turned around! I found the trouble finally, and the practical introduction on the Lehigh

Valley road was the result. The system was sold to a very wealthy man, and he would

never sell any rights or answer letters. He became a spiritualist subsequently, which

probably explains it." It is interesting to note that Edison became greatly interested in the

later developments by Marconi, and is an admiring friend and adviser of that well-known

inventor.

The earlier experiments with wireless telegraphy at Menlo Park were made at a time

when Edison was greatly occupied with his electric-light interests, and it was not until the

beginning of 1886 that he was able to spare the time to make a public demonstration of

the system as applied to moving trains. Ezra T. Gilliland, of Boston, had become

associated with him in his experiments, and they took out several joint patents

subsequently. The first practical use of the system took place on a thirteen-mile stretch of

the Staten Island Railroad with the results mentioned by Edison above.

A little later, Edison and Gilliland joined forces with Lucius J. Phelps, another

investigator, who had been experimenting along the same lines and had taken out several

patents. The various interests were combined in a corporation under whose auspices the

system was installed on the Lehigh Valley Railroad, where it was used for several years.

The official demonstration trip on this road took place on October 6, 1887, on a six-car

train running to Easton, Pennsylvania, a distance of fifty-four miles. A great many

telegrams were sent and received while the train was at full speed, including a despatch to

the "cable king," John Pender. London, England, and a reply from him.[17]

[17] Broadly described in outline, the system consisted of an induction circuit obtained

by laying strips of tin along the top or roof of a railway car, and the installation of a

special telegraph line running parallel with the track and strung on poles of only medium

height. The train and also each signalling station were equipped with regulation

telegraphic apparatus, such as battery, key, relay, and sounder, together with inductioncoil

and condenser. In addition, there was a transmitting device in the shape of a musical

reed, or buzzer. In practice, this buzzer was continuously operated at high speed by a

battery. Its vibrations were broken by means of a key into long and short periods,

representing Morse characters, which were transmitted inductively from the train circuit

to the pole line, or vice versa, and received by the operator at the other end through a

high-resistance telephone receiver inserted in the secondary circuit of the induction-coil.

Although the space between the cars and the pole line was probably not more than about

fifty feet, it is interesting to note that in Edison's early experiments at Menlo Park he

succeeded in transmitting messages through the air at a distance of 580 feet. Speaking of

this and of his other experiments with induction telegraphy by means of kites,

communicating from one to the other and thus from the kites to instruments on the earth,

Edison said recently: "We only transmitted about two and one-half miles through the

kites. What has always puzzled me since is that I did not think of using the results of my

experiments on `etheric force' that I made in 1875. I have never been able to understand

how I came to overlook them. If I had made use of my own work I should have had longdistance

wireless telegraphy."