there were engines which ran by cold as well as those driven by heat. The snow-fields of winter then, as well as the great arid plains of summer, have for some time been used to make and store up power, which is used only as wanted.
A striking landscape feature is the great number of windmills, stately, picturesque and beautiful, which lazily flap their sails or merrily spin with the brisk breeze, generating and storing up power for the houses upon which they are perched. These mills are let run full speed in the fiercest storms; the surplus of power going to the owner's storage system, to be used when wanted, or contributed to the common stock in ease of need.
Railway cars are made very largely of aluminum and paper, thus possessing great stiffness, lightness and strength.
Many new varieties of steel have made their appearance; boron and silicon being used indifferently with carbon in forming combinations with iron, which possesses properties never before seen in steels of any kind.
The hardening of copper has been rediscovered, and for twenty-five or more years this
