Rubber is a substance of so many important characteristics that
its uses are countless. It is used for certain purposes because it
stretches, for others because it is airtight and watertight, for
others because it is a non-conductor of electricity, for others
because it is shock-absorbing, and for others because it is
adhesive.

It is on rubber that infants cut their teeth; after all the teeth
are gone old age makes use of rubber in plates for false teeth.
Ten million motorists and other millions of cyclists in the United
States ride on rubber tires that are durable, noiseless and
airtight. Balloons of rubber float aloft, and huge submarines plow
their routes beneath the ocean's surface propelled by electricity
stored in great rubber cells. Sheathed in rubber, the lightning
makes a peaceful way through our homes, offices and factories,
furnishing light and telephone service. Divers sink out of sight
beneath the waves in rubber suits. Rubber air-brake hose on
railroad trains makes safe the travel of a nation, air-drill hose
rivets our ships, fire hose protects the properly in city and town
and garden hose brings nourishment to our growing plants. Rubber
clothing protects against storm and rubber footwear guards us
against cold and wet. Tennis balls and golf balls and rubber-cored
baseballs give healthful sport to the millions. In hospitals and
medical work the uses of rubber are without number.

To select the most important use to which rubber is put would be
difficult. One student of the subject says:

"Of all the applications of rubber, that of packing for the steam
engine and connecting machinery appears to have been the most