ly convenient
light-sources of to-day there is a great interval, consisting, as
appears retrospectively, of small and simple steps long periods apart.
Measured by present standards and achievements, development was slow at
first and modern man may be inclined to impatience as he views the
history of light and human progress. But the achievements of early
centuries, which appear so simple at the present time, were really great
accomplishments when considered in the light of the knowledge of those
remote periods. Science as it exists to-day is founded upon proved
facts. The scientist, equipped with a knowledge of physical and chemical
laws, is led by his imagination into the darkness of the unexplored
unknown. This knowledge illuminates the pathway so that hypotheses are
intelligently formed. These evolve into theories which are gradually
altered to fit the accumulating facts, for along the battle area of
progress there are innumerable scouting-parties gaining secrets from
nature. These are supported by individuals and by groups, who verify,
amplify, and organize the facts, and they in turn are followed by
inventors who apply them. Liaison is maintained at all points, but the
attack varies from time to time. It may be intense at certain places and
other sectors may be quiet for a time. There are occasional reverses,
but the whole line in general progresses. Each year witnesses the
acquirement of new territory. It is seen that through the centuries
there is an ever-growing momentum as knowledge, efficiency, and
organization increase the strength of this invading army of scientists
and inventors.

The burning fagot rescued mankind from the shackles of darkness, and the
grease-lamp and tallow-candle have done their part. Progress was slow in
those early centuries because the great minds of those ages
philosophized without a basis of established facts: scientific progress
resulted more from an accumulation of accidental discoveries than by a
directed attack of philosophy supported by the facts established by
experiment. It was not until comparatively recent times, at most three
centuries ago, that the great intellects turned to systematically
organized scientific research. Such men as Newton laid the foundation
for the tremendous strides of to-day. The store of facts increased and
as the attitude changed from philosophizing to investigating, the
organized knowledge grew apace. All of this paved the way for the
momentous succ