In Glorious Multiplane - 4
Again, it was applied for by Bill Garity on behalf of Walt Disney Productions, filed May 8th, 1939, granted April 28th, 1942. It thus was filed between the patents of the last two postings.
This patent introduces the "photometric device" and its workings, and shows that the background could be mounted at an angle using a mirror. Otherwise, it is just a simplified version of the patent applied for half a year earlier!
Or am I missing something?