"To understand the system," said Mr. Doane, "let us follow the course of a message from St. Petersburg to San Francisco. The operator at St. Petersburg sends it to the central office of his county by his sympathetic instruments. From that central office it is sent to the section in this city designated 'Continent;' there it is received, and sent to 'The World,' or central office, by pneumatic tubes. At 'The World' it is assorted from the hundreds dropping from the tubes, and sent in a tube to the 'West' section. Here it is received, and sent to the floor named 'California,' handed to an operator, and transmitted to the central office of California, and by them to the city of San Francisco. The time of transit of such a message of twenty words, from St. Petersburg to San Francisco, is thirty minutes."
"Quick work, that!" exclaimed Cobb, admiringly.
"But a more peculiar illustration of the system," continued Mr. Doane, "is exemplified in the sending of a message from Portland, Oregon, to Vancouver, Washington. These cities are but fifteen miles apart; yet the message from the former city is sent to its central office, thence to the 'West' section in this city, thence by tube to the next floor, thence to the central office of Washington, and thence to Vancouver. Now I will show you the instruments," and he motioned them to follow him to the lower end of the room.
Here Cobb for the first time examined the great invention of his old friend and master, Jean Colchis.
On a table were set an ordinary relay, sounder and key, instruments which were familiar to Cobb, who had thoroughly studied the electric telegraph system of his day. The relay only differed from those used in former years in that it had no large and heavy armature in front of its poles, but in its place was a small, bright needle swinging on a vertical pivot. The short end of the needle was held by two delicate springs, pulling in opposite directions. The needle was metallically connected through a local battery to an ordinary sounder, and thence the current was carried to a little stud near the extreme end of the short arm of the needle.
The relay was connected through its keys to another local battery.
If the key was closed--that is, pressed down so as to form a metallic connection--the relay magnets were magnetized by its local battery, and the little needle was drawn toward them by their attraction, until the short arm of the needle rested against the little stud. This touching of the needle to the stud closed the circuit of the second local battery, and the sounder armature answered to the influence. If the key was opened, the circuit was broken, the needle was drawn back by its little spring and the local current of the sounder disrupted. With the exception of the needle, the whole apparatus was precisely similar to that employed in telegraphing in 1887.