How about this one. It is a bit of a blast from the past but there is some suggestion that it may still be out there in some of the old brass telescopes.
RAS thread An obsolete standard for eyepiece barrels. It consisted of a screw thread 1¼ inches in diameter with a pitch of
1/16 inch, derived from a standard gas-pipe fitting. It was introduced by the Royal Astronomical Society (RAS), but was abandoned in the 1970s in favour of push-fit eyepieces.
I have to admit I still own a push-fit draw tube with this thread on the eyepiece end.
