I have in my possession (note that I didn't say "own"; it's a long story, the end of which is yet to play out) a 20" Gurley Hell Gate transit with an optical plummet. The S/N starts with TE, followed by a 4-digit number. According to How Old Is My Gurley, the code used is as follows:
W A N T G U R L E Y
0 1 2 3 4 5 6 7 8 9
That would put the year of manufacture at 1938. However, Gurley didn't patent its optical plummet until 1960, and the gun certainly doesn't look like it was made in 1938. Is there an alternate coding scheme out there somewhere?
This optical-plummet transit has a serial number of TY1482 and is plainly stated as being manufactured in the 1960s. So much for the "WANTGURLEY" theory...although I think it works for older instruments.
good luck
> This optical-plummet transit has a serial number of TY1482 and is plainly stated as being manufactured in the 1960s.
I found another data point: the one I'm holding is marked Teledyne Gurley. The Gurley website says that Teledyne purchased Gurley in 1968, and discontinued production of survey instruments in 1980. That pretty much ensures that this one is post-1960.
My guess
is that the "T" in the serial number might stand for Teledyne. The "E"....who knows.
BTW - We had two of those at a firm I worked at in the '70s. I believe they also were labeled Teledyne. They were not bad instruments at all. I remember the optics were very clear. Not that much more powerful than the K&Es we used, but a lot clearer.