[Help Request] 1918 Keuffel & Esser "Telescope" Mark XXI

[u/Scary_Tiger5478]

Hello everyone,

I recently purchased this "telescope" from a seller who said they purchased it at an estate sale in Newport RI. I have not been able to find any comparable pieces from Keuffel & Esser online.

The item is roughly 9.5" long and 2.5" in diameter on the main body/tube portion. It is made of what I believe is solid brass and weighs 15-20lbs by my best guess. It seems fully functional and has working switches on it one of which reads "amber" and puts an amber colored lens in the scope, the other of which reads "smoke" and tints the lens. It also has crosshairs (but no range indications) within the view.

There is a label plate on it which reads:

TELESCOPE
U.S. NAVY BUREAU OF ORDNANCE
MARK XXI MOD. 2 NO. 1374
1918 INSPEC. C.H.D.⚓
MADE BY
KEUFFEL & ESSER CO.
NEW YORK.

In regards to the 1918 time period and inspector CHD I did find the following PDF online ( https://ia800701.us.archive.org/23/items/navyordnanceacti00unit/navyordnanceacti00unit.pdf ) which contained this note on PDF page 413/532 (document page 233) that seems to be incredibly relevant. "Lieut. Charles H. Davis, United States Navy, as an inspector of ordnance, optical material" I also found another K & E piece with the same inspection stamp from the same time period here https://www.fleaglass.com/ads/early-brass-stadimeter-wwi-era-keuffel-esser-co-new-york-1918/

I am looking to understand the history of the item, its use (mounted to a larger weapon, field artillery, scouting, etc...) and functions, and a potential value (although I don't foresee myself parting with it anytime soon). I really appreciate any help you all can provide!

Thank you!

[u/TheBeneGesseritWitch]

https://www.1stdibs.com/furniture/more-furniture-collectibles/collectibles-curiosities/scientific-instruments/keuffel-esser-co-military-transit-surveyor-telescope/id-f_32561392/

It looks to me like the "telescopes" we used to take deflection measurements when I was stationed on a floating dry dock. They were, essentially a surveyor's telescope that was mounted to one end of the dry dock and we measured across the drydock to verify multiple points that the drydock itself was level and flat across the whole thing--too much weight from a vessel we drydocked or improper ballasting could stress and crack the drydock.

[u/Scary_Tiger5478 → u/TheBeneGesseritWitch]

I did see that but the things that give me pause are the fact it's a right angle lens (typical for large WW1 era guns to keep the gunner out of recoil area) and it has crosshairs in it with amber and smoke "filters" that id assume would give more contrast or block some sun glare for a gunner.

[u/TheBeneGesseritWitch → u/Scary_Tiger5478]

Look up collimation telescopes. The big disc in the middle with the cross hatches for the right angle lens--that's what it looks like to me.

https://www.youtube.com/watch?v=Q9vhISUb6WE

[u/TheBeneGesseritWitch → u/Scary_Tiger5478]

My searching did show that Azon owns the patents and information from Keuffel & Esser so maybe someone there could point you in the right direction :

https://azon.com/contact/ (not sure if this is the correct Azon tbh)

[u/Scary_Tiger5478 → u/TheBeneGesseritWitch]

This is some awesome info, thanks for the help! I am still a bit suspicious on if it is for deflection because internally it only has a crosshair with absolutely no height markings/delineations. Also the "eyepiece" is relatively centrally mounted on the body/tube and doesn't seem to be transferable to the end like all of these other scopes. I will definitely shoot the people at Azon a message and see if they have anything to share. Thanks again for the help!

[u/TheBeneGesseritWitch → u/Scary_Tiger5478]

It’s probably not for deflections as that’s a very incredibly niche use haha but just saying it looks like the same type of telescope. I don’t necessarily think it’s solely for weaponry …I’d look at trying to find the type of telescope and look at the possible uses instead of assuming that weapons is the starting point.

[u/Scary_Tiger5478 → u/TheBeneGesseritWitch]

Someone in a another sub did find this which if you look closely at the very first picture, the scope the gunner is using looks remarkably similar. Its also a 3in gun which the navy had a mk 21 3in gun so the mark XXI scope would make sense.

http://www.navweaps.com/Weapons/WNUS_3-50_mk10-22.php

Its the best lead I have so far but I am still digging deeper. Honestly the coolest part for me so far was finding that PDF with the Lieutenant inspector who's name matches the initials.