THE ART OF ILLUMINATION - PREFACE. SINCE the first edition of this book was published profound and revolutionary changes have taken place in the available materials of artificial illumination. Among electrical illuminants entirely new types of arc light have come into general use, and the carbon incandescent lamp is being rapidly pushed into obsolescence by the metallic filament lamps which now dominate electric lighting practice. In the field of gas lighting, the inverted mantle burners of both large and small capacity, and the high pressure mantle burners, have pushed their way to the front and radically changed the conditions of economy which previously existed. Auxiliaries of every kind, and particularly shades and reflectors of greatly im- proved types, have been so multiplied as to meet almost every possible requirement. All these considerations have made neces- sary a very complete revision of the parts of this volume dealing with practical lighting. Moreover, the art of illuminating engi- neering has been enriched by a large amount of valuable experience within the past few years, and its principles are now founded on a more secure scientific basis. The general principles of the art, however, remain the same and its importance in practical life is at last being adequately appreciated. MARCH, 1912. Vll 257828 V CONTENTS. CHAP. PAGE PREFACE vii I. LIGHT AND THE EYE 1 II. PRINCIPLES OF COLOR 25 III. REFLECTION AND DIFFUSION 37 IV. STANDARDS OF LIGHT AND PHOTOMETRY 52 V. THE MATERIALS OF ILLUMINATION ILLUMINANTS OF COM- BUSTION . 77 VI. THE MATERIALS OF ILLUMINATION INCANDESCENT BURNERS 99 VII. THE ELECTRIC INCANDESCENT LAMP 116 VIII. THE ELECTRIC ARC LAMP . . 150 IX. SHADES ANDREFLECTORS 184 X. DOMESTIC ILLUMINATION 207 XI. LIGHTING LARGE INTERIORS ……… 233 XII. EXTERIOR ILLUMINATION ………. 279 XIII. DECORATIVE AND SCENIC ILLUMINATION 316 XIV. THE ILLUMINATION OF THE FUTURE 336 INDEX 345