Here is Keller's US patent for 45/45 disk cutting: http://www.google.com/patents/US2114471 According to this web page: http://www.stokowski.org/Harvey_Fletcher_and_Bell_Labs_Stereo.htm (which accurately quotes some liner notes to the two Bell Labs LPs, which own; I cannot say for sure other info is true), The Stokowski stereo recordings were indeed two cutters somewhat similar to Emory Cook's method, but of course for wide-groove. Keller's patent was awarded in 1938. I don't think Keller's patent "lapsed" as stated on that web page. I do think Westrex inherited the patent and this collected a lease and license fee on their stereo cutters (the fees were not so onerous as that Westrex wasn't the first "industry standard" stereo LP cutter). -- Tom Fine ----- Original Message ----- From: "Paul Stamler" <[log in to unmask]> To: <[log in to unmask]> Sent: Saturday, August 30, 2014 4:01 PM Subject: [ARSCLIST] Blumlein's stereo patent... > ...is here: > > http://www.doramusic.com/patents/394325.htm > > Peace, > Paul > >