(A forty-watt lamp produces about 10 foot-candles on a surface two feet away.) A survey made by Tinker in 1939 revealed that many factories were far below the standard for effective illumination.

Close inspection requires 500 foot-candles proofreading, 150 general office work,100 wrapping and labeling, 50 dishwashing, 30 loading packages, 20 hotel lobby, 10. The following recommended levels take into account both efficiency and comfort, and are based upon widely accepted research performed by Blackwell (1959). However, this is merely a general finding since the optimal amount of light differs widely from one type of work to another. Studies show that vision improves sharply when low level illumination is increased, even a small amount, but with further increases the improvement becomes slower and eventually levels off. A small, black-on-gray highway sign requires more illumination than a large, clearly printed black and white sign and finely detailed articles moving rapidly along an inspection belt must be examined under more intense light than large, crude objects. But in determining the optimum level of light, the character of the object under observation-its size, and the amount of brightness, contrast, and detail it contains-as well as the time allowed for seeing must be taken into consideration.

Our ability to perform tasks that require visual discrimination is greatly influenced by lighting conditions.

Illuminate definition a