May 1, 1915.] 



THE INDIA RUBBER WORLD 



425 



70,000 communities. The plant of the American Telegraph & 

 Telephone Co. and it s associated companies alone represents an 

 investment ol $850,000,000, The army of men and women en- 

 gaged in its operation, exclusive of those employed by con- 

 necting companies, numbers 160,000. I he messages transmitted 

 over its liiic^ number approximately 9.000,000,000 a year; equiva- 

 lent to 26,000,000 messages a day. or more than 1,000,000 

 hour throughout the twenty-four. When Dr. Hell sent his mi 

 sage by wire over .i. J iKi miles of line to Mr. Watson, hi 

 only a part of the entire telephone system of this country, which 

 embraces 9,000,000 telephones bound together by an intercom- 

 municate network of J 1,000.000 miles oi wire. 



Strange as it may seem, the telephone uses an extremely feeble 

 electrical current, and yet that current must respond sensitively 

 to the sound waves set up bj the human voice and ranging all 

 the way from a modest 200 to something more than 2,000 

 vibration a econd. Hiese minute waxes must speed along ovei 

 the wires without breaking the rhythm of their procession; there 

 must be ti" jostling or confusion, and each undulation musl 

 reach its destination with its characteristic shape, for upon this 

 particular factor hinges the success of intelligible reproduction 

 of the mes 



Now the part that rubber plays is that generally of an insulator, 

 a protecting cloak that keeps the feeble current within bounds 

 and prevent it going astray along the metallic path laid out for 

 it. There are critical stages in the travel of each sound-wave 

 where no other medium serves so well to prevent this harmful 

 leakage, despite the fact that the prod ol economy has sent 

 the engineers hunting broadcast for a cheaper substitute The 

 storj of rubber's efficiency begins the moment you start to use 

 the telephone. The line is automatically opened by the taking 



in coming over the wires. Therefore the receiver must be 

 fashioned of that material which will serve best to guard these 

 vibrations at the moment of their delivery to the auditor. Ac- 

 cordingly, the telephone engineer has found that india rubber 

 will answer for this part of the apparatus more efficiently than 

 .in\ i ither material. 



Speaking from within the home, the hotel, the office, or any 

 other public structure, rubber shields the current from the in- 

 strument down through the building until the connection is made 

 with the outside line, he it an ! or an underground con- 



ductor there. A tidj house wifi sees to it that the floors and 

 aids an' duly washed from time to time, and tile same 

 try precautions are taken in anj well kept building, there- 

 fore there is the danger of moisture reaching the telephone wires, 

 and the fear of dampness is also present when the conductors 

 are run within the walls, as is commonly the case- in hotels, sky- 

 scrapers and other business edifices. Rubber coatings for all of 



these \\ire~ ,,ie necessary to prevent short-circuiting and to lead 

 the electrical currents in the way they should go. Therefore, th( 



intramural leads of nn . m ,,i tin i '>,000,000 telephones must 



be insulated with rubber until they have joined the overhead 

 wires or have effected their junction with the underground 

 cables. 1 he latter, because they are sealed inside of leaden jack- 

 els and safe from thi ol moisture, are insulated by means 

 of paper, which answers well enough today. The weakness of 

 the current permits this so long as the covering of lead is there 

 to keep out the dampness. 



But, hen , the answering voice from the number called 



for, india rubber again figures importantly in the line. It is not 



ecessary here to attempt to describe the details of telephone 



switchboards, but whether the switchboard in question be thai ol 



Alexander G. Bell (Center of Group) Talking in Xew York with Mr. Watson in San Francisco. On His Right. U. N. 

 Bethell, Senior Vice-President of American Telephone & Telegraph Co.; on His Left, Mayor Mitchel, of New York. 



down of the receiver, and that receiver casing is made of hard 

 rubber. Why? Because that substance has certain physical 

 qualities that make it superior for that employment. Therefore, 

 every time any one of the 9,000,000 instruments in the United 

 Stale, is used a debt of thanks is due to india rubber. Possibly 

 we can be a bit more specific. 



The transmitter has the benefit of the vocal waves as they 

 issue from the speaker's mouth with their maximum vigor, while 

 the receiver gets these waves enfeebled by the journey they make 



the business office, the hotel, the local district, or central, every 

 time the plugs of the connecting circuit are shoved home the 

 vitallj necessary insulation is furnished by rubber. True, the in- 

 dividual amount of rubber in each plug is not great — it isn't large 

 because the stuff is so efficient — but it is indispensable for that 

 i . and man} millions of plugs are employed in the multitu- 

 dinous ramifications of the telephone as it reaches into the public, 

 the private and the domestic walks of life. Again, don't let us 

 forget that there is the toll-line switchboard to be considered 



