into a reality.  He worked for ten years on the problem before the “lucky accident” came to him.  One day in 1839 he happened to drop on the hot stove of the kitchen that he used as a laboratory a mixture of caoutchouc and sulfur.  To his surprise he saw the two substances fuse together into something new.  Instead of the soft, tacky gum and the yellow, brittle brimstone he had the tough, stable, elastic solid that has done so much since to make our footing and wheeling safe, swift and noiseless.  The gumshoes or galoshes that he was then enabled to make still go by the name of “rubbers” in this country, although we do not use them for pencil erasers.

Goodyear found that he could vary this “vulcanized rubber” at will.  By adding a little more sulfur he got a hard substance which, however, could be softened by heat so as to be molded into any form wanted.  Out of this “hard rubber” “vulcanite” or “ebonite” were made combs, hairpins, penholders and the like, and it has not yet been superseded for some purposes by any of its recent rivals, the synthetic resins.

The new form of rubber made by the Germans, methyl rubber, is said to be a superior substitute for the hard variety but not satisfactory for the soft.  The electrical resistance of the synthetic product is 20 per cent, higher than the natural, so it is excellent for insulation, but it is inferior in elasticity.  In the latter part of the war the methyl rubber was manufactured at the rate of 165 tons a month.

The first pneumatic tires, known then as “patent aerial wheels,” were invented by Robert William Thomson of London in 1846.  On the following year a carriage equipped with them was seen in the streets of New York City.  But the pneumatic tire did not come into use until after 1888, when an Irish horse-doctor, John Boyd Dunlop, of Belfast, tied a rubber tube around the wheels of his little son’s velocipede.  Within seven years after that a $25,000,000 corporation was manufacturing Dunlop tires.  Later America took the lead in this business.  In 1913 the United States exported $3,000,000 worth of tires and tubes.  In 1917 the American exports rose to $13,000,000, not counting what went to the Allies.  The number of pneumatic tires sold in 1917 is estimated at 18,000,000, which at an average cost of $25 would amount to $450,000,000.

No matter how much synthetic rubber may be manufactured or how many rubber trees are set out there is no danger of glutting the market, for as the price falls the uses of rubber become more numerous.  One can think of a thousand ways in which rubber could be used if it were only cheap enough.  In the form of pads and springs and tires it would do much to render traffic noiseless.  Even the elevated railroad and the subway might be opened to conversation, and the city made habitable for mild voiced and gentle folk.  It would make one’s step sure, noiseless and springy, whether it was used individualistically as rubber heels or collectivistically as carpeting