[BifRayRock]

Originally Posted by MichaelRyerson

'each...cover saved 500 pounds of metal'?? How? Manhole covers are seriously heavy but still, they can be moved by one man with a long-handled hook and some elbow grease. Are they suggesting manhole covers weighed 500 pounds?

Just a guess, but the weight estimate may have been factoring in some corresponding metal superstructure and mating surface that is typically embedded in the street with metal covers. The wooden cork versions do not look as though they used this setup.

http://www.sewerhistory.org/images/acn/8.gif


Or, possibly foundries used a very special top secret type of pig iron that was susceptible to evaporation when exposed to light?

I do understand that this is not LA related, but there may be a slight Noir factor. http://www.sewerhistory.org/images/m...1937_mid01.jpg