Armour Engineer Volume 3-4

Armour Engineer Volume 3-4

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This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1911 edition. Excerpt: ...absorbed and 480 lumens are reflected to the floor. Of the total incident illumination of 1200 lumens on the floor 1080 lumens are absorbed and 120 lumens reflected. Of the 600 lumens at the ceiling 120 come from the floor, leaving 480 to be supplied by the illuminants. Similarly of the 1200 lumens at the floor, 480 come from the ceiling, leaving 720 lumens to be supplied by the lamps. Thus we have _ Effective or C0-efficient Lumens Area sq. ft. Intensity. incident of absorp-absorbed. lumens. tion. Ceiling........... 300 2 600.20 120 '/alls............ 700 l 700.40 280 Floor............. 300 4 1200.90 1080 2500 1480 Lumens received Lumens supLumens reflected. by reflection. plied by lamps. Ceiling........... 480 120 480 Walls............ 420 420' 280 Floor............ 120 480 720 1020 1480 '.-ssumed. The discussion, thus far, on calculations, has dwelled on the determinations of illumination intensities due to the luminous source. It is often desirable to know the distribution of light from a luminous source which will give an approximately uniform illumination. In order to obtain uniform illumination from one lamp recourse is made to the expression where Eh is the horizontal illuminination in foot-candles, a the angle which the luminous rays make with a vertical through the source, I, the candlepower of tthe source of light a degrees from the vertical, and I1 the height of the lamp above the working plane. For uniform illumination E and h, will be constant and I, at various values of a must' vary inversely as cos' a. A polar curve (Z4) showing this relation is given in Fig. 9, which represents the distribution of intensity of a lamp in a vertical plane which would uniformly illuminate the area beneath it. Obviously, more

Product details

  • Paperback | 158 pages
  • 189 x 246 x 9mm | 295g
  • United States
  • English
  • black & white illustrations
  • 1236950631
  • 9781236950635