Continuing the theme of weighty volumes, another one I’ve used to hold things down and flat is the Machinery’s Handbook.
If you only ever have one engineering volume in your library, this is the one to have. My copy is the 1928 third edition. It covers pretty much everything, except perhaps how to get to the moon since they hadn’t achieved it back then (in fact if you think about it, the frontline fighter planes of developed countries were biplanes back then).
It also is well presented with finger hole bookmarks and coloured edge paper.