Plywood is simply veneer over another surface. The technique is old.
The wood core is likely thick, e.g. 1/8" and veneers half that or less.
It was a matter of putting 'exotic' wood display with a stable core.

Martin

On 4/10/2016 9:28 AM, John McCoy wrote:
"dadiOH" wrote in :

DerbyDad03 wrote:

I think that they are solid wood (?) because I don't see any plies.
Did they use plywood for drawer bottoms back then?

Is the bottom nailed to the borrom edge of the back?

This pictu http://imgur.com/Y7aKfPU appears to show the
bottom nailed in 3 places at the back.

Plywood was invented before 1900, but I don't think it came
into common use until after WW1.

You may be able to take care of the sag by screwing (rather
than nailing) the bottom to the back in several places.

John