5 66 THE POPULAR SCIENCE MONTHLY. 



expressed by the word induction. Briefly, it may be put thus: that, 

 when a strong electric current is passing on a wire, it has the faculty 

 of setting up a current of opposite character in any wire not then 

 working, or working with a feebler current, that may be in its vicin- 

 ity. The why or the wherefore cannot be explained, but there is the 

 fact. 



" In various recent articles on the telephone, mention has been 

 made of 'contact ' as the cause of disturbance. This word, however 

 although it has been used by telegraphists, is misleading, and can 

 only be used as an endeavor to express popularly an electric fact. 

 Actual contact of one wire with another would spoil the business alto- 

 gether. A wire bearing an electric current seems to be for the time 

 surrounded, to an undefined distance, by an electric atmosphere, and 

 all wires coming within this atmosphere have a current in an oppo- 

 site direction set up in them. This is as near an explanation of the 

 phenomena of induction as the state of telegraph science at present 

 affords. Now, the telephone works with a very delicate magnetic 

 current, and is easily overpowered by the action of a stronger current 

 in any wii - e near which the telephone-wire may come. To work prop- 

 erly, it ' requires a silent line.' 



" In the place where the observations were made, there were a 

 large number of wires traveling under the floor, along passages to the 

 battery-room, and to a pole on the outside, whence they radiate, or 

 out to a pipe underground, where many gutta-percha-covered wires 

 lie side by side. On applying the ear to a telephone joined into a cir- 

 cuit working in such an office, a curious sound is heard, comparable 

 most nearly to the sound of a pot boiling. But the practised ear 

 could soon separate the boiling into distinct sounds. There was one 

 masterful Morse instrument probably on the wire lying nearest the 

 one on which we were joined up whose peremptory ' click, cli-i-i-ck, 

 click,' representing ' dot, dash, dot ' on the printed slip we read from, 

 could be heard over all. Then there was the rapid whir of a fast- 

 speed transmitter sending dots and dashes at express speed by me- 

 chanical means ; and, most curious of all, the ' rrrrr-op, rr-op, rrrrrrr- 

 rrrrrr-op, rrrrr-op, rr-op ' of the A B C, or printing-instrument, the 

 deadliest foe to the telephone in its endeavors to gain admission into 

 the family of telegraph-instruments. There may be reason in this, for 

 as the ABC, or printing-instrument, is the instrument used for pri- 

 vate telegraphy, or for the least important public offices, because it 

 requires no ' code ' to be learned by the manipidator, so it would 

 likely be the first to be displaced if an acoustic telegraph permanently 

 took the field. So the sentient little ABC opens its mitrailleuse-fire 

 on the intruder, on whose delicate currents, in the words of an accom- 

 plished electrician, it plays 'old Harry.' The peculiar character of 

 the sounds we borrow on the telephone from this instrument arises 

 from the fact that, as the needle flies round the dial, a distinct current 



