When I was a child, I remember owning or borrowing a book which had a
really cool two page drawing of the entire process of making lumber. I
believe the book was some sort of children's encyclopedia. There was a
mountain, and it showed lumberjacks cutting down trees. Then, the
trees were dragged to a flume of some sort, and they floated down to a
river. The logs floated down the river, and lumberjacks made sure that
the logs got diverted over to the lumbermill, and then the logs were
stripped of bark and then cut into standard size pieces of lumber. I
remember it as one of the best illustrations of a process that I have
ever seen. I hope that someone else remembers this drawing, and the
name of the book that it was in. If someone actually has the book and
can mail me a copy of those pages, I will happily pay even more.

Martha --

Highly likely sources are old versions of World Book or Encyclopedia
Americana.  We have a 1977 version of the World Book, which under the
"lumber" entry has the image below.  This is a black-and-white image,
which I've posted to give you an idea of World Book's illustration
style, in hopes that it matches what you're seeking:
http://www.lucidmatrix.com/uploads/temp.jpg

We keep a couple of old encyclopedias for historical reference here at
home. Your local librarian can probably give you a good idea where
1950s collections go to rest.

Best regards,

Omnivorous-GA