Illuminating Engineering Society, Association of Public Lighting Engineers (Great Britain) · [London] · leaf 382
lays such an im-portant part in daylight calculations, itmay be well to add a few notes on themeasurempijt of such angles, and their usein photometry. This matter has beendealt with in an article in The Illumina-ting Engineer for January 1912, byProf. Silvanus P. Thompson. Solid angles are measured… … (or sterean), and the above formulamakes use of solid angles expressed interms of this unit. The whole solid angleof space around any point will be 47rsteradians. A window 6 feet high and3 feet wide at a distance of 30 feet sub-tends approximately 6X3 1 ,. (30? = 50 steradian- There is another…
Lighting
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