Bell jars for lettuce?

Sitting inside today, trying to avoid the single-digit temperatures outside, I came across this interesting blog called Inventing Green - the lost history of American clean tech.

It has an article about an article (that's what we bloggers do) that showed how the British, starving for fresh vegetables during World War I, used an innovative low-tech method to extend the growing season for lettuce. The article was originally published in a 1918 edition of National Geographic (see, my dear wife, there is a reason to save each and every edition of this great magazine).

At any rate, the article showed how Britain was able to grow food for 40 of 52 weeks. Turns out these bell jars were adapted from a French idea of intensive gardening. The French called them cloches.

The blog later states how some in the U.S. later discovered this practice. Too bad that a good idea has to be discovered again and again.

I'm going to try it this year. One other benefit to using a bell jar over heads of lettuce - I challenge the evil rabbits to get at my lettuce!

Addendum: I searched Youtube for some videos on using bell jars for lettuce, but couldn't find one. However, this video shows a pretty inexpensive form of backyard greenhouse.