Artificial Light | Page 2

THE ELECTRIC INCANDESCENT FILAMENT LAMPS 127
XI THE LIGHT OF THE FUTURE 143
XII LIGHTING THE STREETS 152
XIII LIGHTHOUSES 163
XIV ARTIFICIAL LIGHT IN WARFARE 178
XV SIGNALING 194
XVI THE COST OF LIGHT 208
XVII LIGHT AND SAFETY 225
XVIII THE COST OF LIVING 238
XIX ARTIFICIAL LIGHT AND CHEMISTRY 256
XX LIGHT AND HEALTH 269
XXI MODIFYING ARTIFICIAL LIGHT 284
XXII SPECTACULAR LIGHTING 298
XXIII THE EXPRESSIVENESS OF LIGHT 310
XXIV LIGHTING THE HOME 325
XXV LIGHTING--A FINE ART? 341
READING REFERENCES 357
INDEX 359

LIST OF ILLUSTRATIONS
Light and Liberty Frontispiece FACING PAGE Primitive fire-baskets
16
Crude splinter-holders 16
Early open-flame oil and grease lamps 17
A typical metal multiple-wick open-flame oil-lamp 32
A group of oil-lamps of two centuries ago 33
Lamps of a century or two ago 56
Elaborate fixtures of the age of candles 57
Flame arc 128
Direct current arc 128
On the testing-racks of the manufacturer of incandescent filament
lamps 129
Carbon-dioxide tube for accurate color-matching 160
The Moore nitrogen tube 160
Modern street lighting 161
A completed lighthouse lens 176
Torro Point Lighthouse, Panama Canal 176
American search-light position on Western Front in 1919 177
American standard field search-light and power unit 177
Signal-light for airplane 232

Trench light-signaling outfit 232
Aviation field light-signal projector 232
Signal search-light for airplane 232
Unsafe, unproductive lighting worthy of the dark ages 233
The same factory made safe, cheerful, and more productive by modern
lighting 233
Locomotive electric headlight 240
Search-light on a fire-boat 240
Building ships under artificial light at Hog Island Shipyard 241
Artificial light in photography 256
Sterilizing water with radiant energy from quartz mercury-arcs 257
Judging color under artificial daylight 272
Artificial daylight 273
Fireworks and illuminated battle-fleet at Hudson-Fulton Celebration
288
Fireworks exhibition on May Day at Panama-Pacific Exposition 289
The new flood lighting contrasted with the old outline lighting 304
Niagara Falls flooded with light 305
Artificial light honoring those who fell and those who returned 320
The expressiveness of light in churches 321
Obtaining two different moods in a room by a portable lamp which

supplies direct and indirect components of light 336
The lights of New York City 337
Artificial light in community affairs 352
Panama-Pacific Exposition 353

ARTIFICIAL LIGHT
I
LIGHT AND PROGRESS
The human race was born in slavery, totally subservient to nature. The
earliest primitive beings feasted or starved according to nature's bounty
and sweltered or shivered according to the weather. When night fell
they sought shelter with animal instinct, for not only were activities
almost completely curtailed by darkness but beyond its screen lurked
many dangers. It is interesting to philosophize upon a distinction
between a human being and the animal just below him in the scale, but
it may serve the present purpose to distinguish the human being as that
animal in whom there is an unquenchable and insatiable desire for
independence. The effort to escape from the bondage of nature is not
solely a human instinct; animals burrow or build retreats through the
instinct of self-preservation. But this instinct in animals is soon
satisfied, whereas in human beings it has been leading ever onward
toward complete emancipation.
The progress of civilization is a long chain of countless achievements
each one of which has increased man's independence. Early man
perhaps did not conceive the idea of fire and then set out to produce it.
His infant mind did not operate in this manner. But when he
accidentally struck a spark, produced fire by friction, or discovered it in
some other manner, he saw its possibility. It is thrilling to picture
primitive man at his first bonfire, enjoying the warmth, or at least
interested in it. But how wonderful it must have become as twilight's

curtain was drawn across the heavens! This controllable fire emitted
light. It is easy to imagine primitive man pondering over this
phenomenon with his sluggish mind. Doubtless he cautiously picked up
a flaming stick and timidly explored the crowding darkness. Perhaps he
carried it into his cave and behold! night had retreated from his abode!
No longer was it necessary for him to retire to his bed of leaves when
daylight failed. The fire not only banished the chill of night but was a
power over darkness. Viewed from the standpoint of civilization, its
discovery was one of the greatest strides along the highway of human
progress. The activities of man were no longer bounded by sunrise and
sunset. The march of civilization had begun.
In the present age of abundant artificial light, with its manifold
light-sources and accessories which have made possible countless
applications of light, mankind does not realize the importance of this
comfort. Its wonderful convenience and omnipresence have resulted in
indifference toward it by mankind in general, notwithstanding the fact
that it is essential to