ThomD
>I'm not sure one has to conjecture that a back saw was only possible at a given point in the development of steel. It could have come into being when similar relative material technology existed. If steel makes it possible for steel to be thin enough that it now seems unsuported, then the same could have happened earlier with a given earlier material brought to a relative degree of pliancy with regard to a given wood. Weren't saws at one time copper? That material can be worked out very thin. This could explain why the technology waxed and wained, if it did. You get a given material pushed to it's limit, then along comes iron and it's like carbon fibre today, and a cycle of development is undertaked, then along comes steel.