It is a pleasant duty to acknowledge the coöperation of various companies in obtaining the photographs which illustrate this book. With the exception of Plates 2 and 7, which are reproduced from the excellent works of Benesch and Allegemane respectively, the illustrations of early lighting devices are taken from an historical collection in the possession of the National Lamp Works of the General Electric Co. To this company the author is indebted for Plates 1, 3, 4, 5, 6, 9, 11, 15, 18b, 20, 21, 29; to Dr. McFarlan Moore for Plate 10; to Macbeth Evans Glass Co. for Plate 12; to the Corps of Engineers, U. S. Army, for Plate 13; to Lynn Works of G. E. Co. for Plates 14, 16; to Edison Lamp Works of G. E. Co. for Plates 17, 24; to Cooper Hewitt Co. for Plate 18a; to R. U. V. Co. for Plate 19; to New York Edison Co. for Plates 22, 26, 30; to W. D'A. Ryan and the Schenectady Works of G. E. Co. for Plates 23, 25, 31; to National X-Ray Reflector Co. for Plate 28. Besides the companies and the individuals particularly involved in the foregoing, the author is glad to acknowledge his appreciation of the assistance of others during the preparation of this volume.
X THE ELECTRIC INCANDESCENT FILAMENT LAMPS 127
Light and Liberty _Frontispiece_ FACING PAGE Primitive fire-baskets 16
A typical metal multiple-wick open-flame oil-lamp 32
A group of oil-lamps of two centuries ago 33
Elaborate fixtures of the age of candles 57
On the testing-racks of the manufacturer of incandescent filament lamps 129
Carbon-dioxide tube for accurate color-matching 160
American search-light position on Western Front in 1919 177
American standard field search-light and power unit 177
Aviation field light-signal projector 232
Unsafe, unproductive lighting worthy of the dark ages 233
The same factory made safe, cheerful, and more productive by modern lighting 233
Building ships under artificial light at Hog Island Shipyard 241
Sterilizing water with radiant energy from quartz mercury-arcs 257
Judging color under artificial daylight 272
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