Soon after exchanges sprang up in several cities, and by August of that year there were 778 Bell telephones in use. From this modest beginning the telephone has grown until on January 1, 1914, there were 13,500,000 telephones in the world, nearly 9,000,000, or over 64 per cent being in the United States. [Illustration: MODERN DISTRIBUTING FRAME When the wires come to this frame they are in numbered order in the cable. The main frame redistributes these wires so that they are arranged according to their call numbers, making it possible to connect any wire with any other wire anywhere that telephone service is installed.] [Illustration: HOW THE WIRES ARE PUT UNDERGROUND Breaking Up the Asphalt Pavement. First Step in Laying an Underground Cable.] [Illustration: Laying Multiple Duct Tile Subway Through Which the Cables Will Run.] [Illustration: Feeding Cable Into Duct as It is Being Pulled Through Subway from the Other End.] [Illustration: A CABLE TROUBLE] The use of the telephone instrument is common, but it affords no idea of the magnitude of the mechanical equipment by which it is made effective. ~UNSEEN FORCES BEHIND YOUR TELEPHONE~ To give you some conception of the great number of persons and the enormous quantity of materials required to maintain an always-efficient service, various comparisons are here presented. [Illustration: TELEPHONES. Enough to string around Lake Erie--8,000,000, which, with equipment, cost at the factory $45,000,000.] [Illustration: WIRE. Enough to coil around the earth 621 times--15,460,000 miles of it, worth about $100,000,000, including 260,000 tons of copper, worth $88,000,000.] [Illustration: LEAD AND TIN. Enough to load 6,600 coal cars--being 659,960,000 pounds, worth more than $37,000,000.] [Illustration: CONDUITS. Enough to go five times through the earth from pole to pole--225,778,000 feet, worth in the warehouse $9,000,000.] [Illustration: POLES. Enough to build a stockade around California--12,480,000 of them, worth in the lumber yard about $40,000,000.] [Illustration: SWITCHBOARDS. In a line would extend thirty-six miles--55,000 of them, which cost, unassembled, $90,000,000.] [Illustration: BUILDINGS. Sufficient to house a city of 150,000--more than a thousand buildings, which, unfurnished, and without land, cost $44,000,000.] [Illustration: PEOPLE. Equal in numbers to the entire population of Wyoming--150,000 employes, not including those of connecting companies.] The poles are set all over this country, and strung with wires and cables; the conduits are buried under the great cities; the telephones are installed in separate homes and offices; the switchboards housed, connected and supplemented with other machinery, and the whole system kept in running order so that each subscriber may talk at any time, anywhere. Where Does Sound Come From?