Fig. 21.-Show window of the boxed-in type illuminated with five single inverted mantle gas lamps installed over glass panels in the ceiling of the window close to the plate glass.

a consequence, will be free from frost during cold weather. The arrangement of the air ducts, ventilators, and lamps causes a current of air to pass constantly across the back of the glass. In any window where sweating is noted, it is merely necessary to arrange the lamps, fixtures, and ventilators in such a manner as to produce a circulation of air over the entire surface of the glass and the trouble will disappear.

In windows fitted as shown in Diagram A, Fig. 23, the openings in the deck should be large enough to permit the lamps to be adjusted from the interior of the window. Transoms above the windows

Fig. 23.-Illustrating three methods of installation for window lighting with gas lamps. A, enclosed type of window, lamps equipped with angle reflectors projecting through openings in the front of the deck of the window. B, the totally enclosed type of window, with glass panels in the front part of the deck and the gas lamps with opaque concentrating reflectors installed above this glass at a sufficient height to enable the reflectors, glassware, and mantles to be removed without difficulty. C, an approved method for the installation of gas lamps in the open type of window. The lamps are concealed in a box built in at the top and parallel with the plate glass, the bottom of this box being fitted with glass panels.

should extend to within 3 inches of the ceiling and should be hinged at the bottom so that when they are open they protect the lamps in the window from draught and prevent undue heat pocketing at the ceiling.

For corner show windows, windows that are shallow, or windows where the display is such that access to the window can be had only at irregular intervals, the type of construction illustrated in Diagram B, Fig. 23, is recommended. The glass panels in the front of this deck are of ripple or cathedral glass which serves to break up the image of the lamp above the glass and to distribute the light effectively

throughout the window without the absorption losses of the ground or sandblasted glass that has been used in the past. In this type of window the lamps should be installed above the glass at a sufficient height to permit the mantles and glassware to be removed. The reflectors should be opaque and of the concentrating type.

Fig. 21 shows a window of this kind in which the lamps are equipped with prismatic glass reflectors. The opaque band with translucent letters at the top of the window serves to cut off the view of the glass panels from the observer on the street.

In deep narrow windows the lighting units may be distributed over the entire deck. A window lighted in this manner is shown in Fig. 22.

For the open type of show window, the construction shown in Diagram C, Fig. 23, is recommended. The two important factors in a window of this type are: first, that the location of the lamps must be such as properly to illuminate the face of the display presented to the observer on the outside and, second, those on the inside of the store should be protected from the glare which would result with a row of open lamps used in this position. The lamps can be shielded from the interior of the store by this method as shown on the diagram. The rear section of this box may be of panelled wood or metal. The bottom of the box should be filled in with panels of ripple glass. Opaque concentrating reflectors should be used. As cathedral glass can be secured in several colors, it is advisable that the framework be arranged so that the glass can be easily removed and, in this manner, the color effects of the lighting can be varied by the use of different colored glass.

There are two practically standard methods used for igniting the lamps in these show windows. First, the jump spark system, the necessary energy for which is supplied by a battery of dry cells and, second, ignition by pilot flames. The gas supply to the lamps can be controlled by a magnet valve operated from the dry cells.

BIBLIOGRAPHY

1 W. A. DURGIN and J. B. JACKSON.—“Semi-direct Office Lighting in the Edison Building of Chicago." Trans. Ill. Eng. Society., 1915, page 698.

2 "Lighting Handbook." Ivanhoe-Regent Works of General Electric Co., 1915.

M. MCMILLAN.-"Better Lighting Supervision Would Preserve Health in New York Office Buildings." L. J., 1916, page 188.

E. L. ELLIOTT.-"Economy." Ill. Eng., 1912, page 623.

CHAS. F. SCOTT.-"Cost and Value of Light." Electric Journal, 1910, page 333.

"Lighting Survey." L. J., 1913, page 206.

7A. O. DICKER and J. J. KIRK.-"Lighting in Downtown Office Buildings." Trans. Ill. Eng. Society, 1915, page 661.

"Lighting a Large Mail Order Mercantile Establishment."

Review and Western Election, 1914, page 384.

Electrical

'Central Station Offices at Ann Arbor." Electrical World, 1914, page 714. F. M. EGAN. "The Lighting of a New York Office Building." L. J., 1914, page 2.

J. D. LEE, JR.—“The Lighting of Post Office Substations in Philadelphia." L. J., 1913, page 288.

J. D. LEE, JR.-"The Lighting of Post Office Substations in Philadelphia." L. J., 1914, page 8.

8 A. L. POWELL. L. J., 1916, page 98.

"Choice of a Semi-indirect Unit for Office Lighting."

C. E. CLEWELL.-"Practical Notes on Illuminating Design." Ill. Eng., 1912, page 140.

P. EVES.-"The Indirect System of Gas Lighting at the Remodeled Offices of the Indianapolis Gas Company." Ill. Eng., 1911, page 366.

J. M. COLES.-"Lighting of the Laclede Gas Light Company's New Building in St. Louis." L. J., 1913, page 295.

T. SCOFIELD and O. H. FOGG.-"Office and Store Lighting." Am. Gas Lt. J., 1915, page 299.

"Lighting of Consolidated Gas Building, N. Y." Gas Age, 1916, page 197. E. J. EDWARDS and W. HARRISON.-"Some Engineering Features of Office Building I ighting." Trans. Ill. Eng. Society, 1914, page 164.

J. P. MALIA. "Office Indirect Lighting." Electrical World, 1913, page 335. C. E. CLEWELL.-"Illumination Design Notes Based on the New Hill Building, New York." L. J., 1915, page 73.

T. H. ALDRICH and J. P. MALIA.—“Indirect Illumination of the General Offices of a Large Company." Trans. Ill. Eng. Society, 1914, page 103.

S. G. HIBBEN.-"General Suggestions for the Proper Installation and Use of Semi-indirect Lighting Fixtures." L. J., 1915, page 145.

H. D. BUTLER and J. A. HOEVELER.-"Indirect Illumination in a Large General Office." L. J., 1913, page 196.

"Comparison of Office Building Lighting Equipments." Electrical Age, 1915, page 41.

A. B. ODAY and R. E. HARRINGTON.-"Illumination Systems for Good Lighting of Offices." Electrical World, 1915, page 814.

C. E. CLEWELL.-"New Lighting in the Engineering Building of the University of Pennsylvania." L. J., 1915, page 196.

W. E. CHAPMAN.-" Artificial Lighting of Typical Offices in State, War, and Navy Department Building." Trans. Ill. Eng. Society, 1915, page 651.

M. SPENCER. "Scientific Illumination of Working Surfaces." Ill. Eng., 1912, page 132.

"Unit Lighting System." Electrical World, 1911, page 1512.

"Drafting Room Indirect Illumination." Electrical World, 1912, page 832.

W. S. KILMER.-"Office Building Lighting." Electrical World, 1912, page 264.

W. S. KILMER.-"The Lighting of an Office Building." Ill. Eng., 1912, page 223.

10 "Handbook on Incandescent Lamp Illumination." Edison Lamp Works of General Electric Co., 1916.

W. N. GOLDSCHMIDT.-"Indirect Lighting in an Insurance Company's Office." Ill. Eng., 1911, page 140.

F. W. WILLCOx.-"The Illumination of the Turbo Drawing Office, The British-Thomson-Houston Co., Ltd." Ill. Eng., 1911, page 319.

G. H. SWANFELD.-"Lighting the Largest Publishing House in America." Ill. Eng., 1911, page 624.

L. H. SULLIVAN.-"Lighting the People's Savings Bank, Cedar Rapids, Iowa." Ill. Eng., 1911, page 631.

S. G. HIBBEN. "When Architect and Engineer Coöperate." page 35.

L. J., 1913,

D. WOODHEAD.-"The Lighting of a Bank and a Large General Office." L. J., 1913, page 292.

"Indirect Lighting of a Bank in Los Angeles." Gas Age, 1914, page 386. F. J. MCGUIRE and F. R. NUGENT.-"The Lighting of New York's Great Municipal Building." L. J., 1914, page 125.

C. M. BUNN.-"Concealed Lighting Fixtures in the Swedish-American Bank, Chicago." L. J., 1914, page 30.

W. R. MOULTON.-"Modern Lighting of a Bank by Reconstruction of Old Fixtures." L. J., 1916, page 102.

C. L. LAW.-"Illumination Test on Semi-indirect and Cove Lighting in a Combined Office and Salesroom." L. J., 1915, page 12.

"Cove Lighting of a Store." Electrical World, 1916, page 378.

11 W. S. KILMER.-"Semi-indirect Lighting Applied to Large Areas." L. J., 1913, page 40.

12 W. N. GOLDSCHMIDT.—“ Jewelry Store Lighting with Indirect Fixtures." L. J., 1915, page 105.

E. J. DAILEY.-" Clothing Store Lighting with Type C Mazda Lamps." L. J., 1915, page 2.

W. R. MOULTON.-"Lighting of Stores and Public Buildings." Electrical Review and Western Electrician, 1916, page 918.

13 A. L. POWELL.-"Large Dry Goods and Department Store Lighting." L. J., 1913, page 142.

C. L. LAW and A. J. MARSHALL.-"The Lighting of a Large Store." Trans. Ill. Eng. Society., 1911, page 186.

T. E. RITCHIE.-"Color Discrimination by Artificial Light." Prog. Age, 1912, page 199.

"Filene Store, Boston." Electrical World, 1913, page 579.

W. S. KILMER.-"Semi-indirect Illumination in a Department Store." L. J., 1913, page 151.

H. W. SHALLING.—“ "Department Store Lighting." Trans. Ill. Eng. Society, 1913, page 17.

"Illumination Features in N. Y. Department Store." Electrical World, 1914, pages 1134, 1145, 1397.