We've seen 2 houses with these windows. Ours was built in 1905 and the other house was built in the 1890's. I do want to preserve them but have yet to take them completely apart. Restoration has barely begun on this house, we believe it is entirely made of redwood (very common wood in Northern California). Some of the details that are in our house, I have never seen elsewhere. This house will be the 8th I will have undertaken restoration. When & if I find out further details I will post the info just in case someone else runs a cross them. Thanks for your info.