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Lighting in Relation to Public Health September 11, 2008

Posted by David Corney in Uncategorized.

Browsing in the library just now, I just came across, and dipped into, a rather elderly book entitled “Lighting in Relation to Public Health” by Dr Janet Howell Clark, published in Baltimore by Williams and Wilkins Company, in 1924. The wonderful “old book” smell came at no extra cost. Something that caught my eye was from Chapter 8, Lighting in Schools. “If possible, unilateral light from the left should be used….” And for rooms that are too wide, “lighting from the left and rear being preferable to lighting from the right and left” (p.92).

Why light from the left? Again, a few pages later, there’s a section on “Lighting Legislation in schools” (p.99). Apparently, designs for new schools should be approved by the State Board of Education or some equivalent body, each state having their own legislation. Examples included, “Indiana: light from left only” and “Minnesota: Light from left, except in very large rooms. Light from east best, west next. North and South light to be avoided in regular study rooms.” Many other states are listed as requiring “light from left, or left and rear” in classrooms.

Why this idea about light coming from the left in schools? I couldn’t see any explanation given in the book, nor any mention of left-light for factories or the home. (Though it did suggest that kitchen lighting should be stronger than dining room lighting, so that crockery is “visibly” clean…) And this amongst plenty of sensible-seeming advice about natural vs artificial light, and the importance of sufficient light in the workplace and so on.

So my first thought was that the author was some crank, or being charitable, that this was some outdated idea that seemed perfectly reasonable in the 1920’s. Anyway, I did a quick google, and via “The Biographical Dictionary of Women in Science” found a little more about the author.

Dr Janet Howell Clark (1889-1969) gained a PhD in Physics from Johns Hopkins in 1913, having graduated from Bryn Mawr College, and was later made professor of biological sciences at the University of Rochester, and Dean of the Women’s College there. Some years later, this post was apparently downgraded from being equal to the Dean of Men, to being subordinate to it (in 1952) so she resigned and returned to Johns Hopkins, eventually retiring at 78.

She was an expert in the effect of radiation on eyesight and diseases caused by low or high levels of lighting (such as glassblowers and iron smelters). She investigated the use of ultraviolet light both as an antibiotic and to prevent rickets in children. She was also greatly concerned about women’s education in general, feeling it was a good thing, and was head of Bryn Mawr school for a number of years, in between various university teaching and research posts.

So clearly not a crank. But why light from the left?

So some more googling, and an explanation that I probably should have thought of myself. In “Electric Lighting” , one Olin Jerome Ferguson of the University of Nebraska, writing in 1920, pointed out that when writing at a desk, it’s helpful if the light doesn’t cast a shadow over your work. So if you’re right-handed, then light from the left would help. And Dr Clark had made it clear that light from the rear means that there’s less glare and excessive contrast for the blackboard at the front of the classroom. So it all makes sense, and I guess it’s so obvious to school designers that Dr Janet Clark didn’t feel the need to explain. My bad.

A final quote of Dr Clark from a chapter on Lighting in the Workplace:

“Cigar factories – Cigars are sorted in respect to color and the varieties of shades of brown are distinguished with difficulty if at all, under yellowish artificial light”

Couldn’t agree more!



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