PREFACE



    A suRvry of the last century reveals it as an age of some
great men and many marvelous achievements.        As the
achievements exceed the giants of the age in number, so, too,
they surpass them  in grandeur.  All the restless activity
of a Napoleoni or the iron policy of a Bismarck have not
wrought upon modern life as did the steam engine. The
great inventions and their adaptation to the needs of human-
ity are the real glories of the nineteenth century.
   Thus new epochs in the development of man have been
brought about by our modern modes of transit and trans-
portation, our steam cars and boats, electric motors, bicycles
and automobile vehicles, as well as our new modes of com-
munication by means of the electric telegraph, telephone, and
phonograph.
   Human life, as it exists now among civilized communi-
ties, owes still more, perhaps, to our new labor-saving ma-
chines and devices.  Of these, our various agricultural im-
plements, our sewing machines, typewriters, and printing
presses are but instances.  The comforts of life have been
immeasurably increased by the universal adoption of things
now termed common and indispensable, such as friction
matches, gas lighting, electric light and appliances, or steel
pens-as well as modern methods of heating, plumbing and
construction. Among the esthetic gains of mankind attained
during this same century must be reckoned such results of
the study of light as photography or the kindred processes of
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