The 3rd edition (1951) of 'A Treatise on Milling and Milling Machines' has been digitized by google and is available at http://babel.hathitrust.org/cgi/pt?id=wu.89089665160;view=2up;seq=6 (thanks MichaelG for the link).
Unfortunately either the copy they digitized is missing pages 67 and 68, or they skipped them by mistake (I've let them know, via their 'Feedback' link).
While it doesn't appear likely they will contain vital information, I really would like to see them for completeness. So if anyone has a hard copy of those two pages that they could share, I would be most appreciative.
Thanks, Roger