Mystery Measuring Stick

[S. Heslop]

Wouldn't a wide blade on top like that tend to block what you are aiming at to a dangerous degree? If there's movement laterally or behind, how can you tell?

I misread the website I linked and it suggests that those tangent sights were used for direct fire in 19th century artillery, so now the blade thing is back to confusing me.

[steampunkpete]

Thank you all very much for your ideas and suggestions.

I think that I am probably right in thinking it is a calibration device for artillery. It's purpose would be something like fine alignment of the computer to the cradle or the piece, so only a very small scale would be needed. It is conceivable that it might be for the setting up of indirect fire equipment.

I think that a visit to the RA museum is now on my to-do list.

Peter

[Joe d]

Found it!  This thing is a ventometer, used for adjusting military rifle sights

http://www.militaryrifles.com/britain/MHVentometer.htm

If you decide you don't need it, let me know

Cheers, Joe

(edited for crap spelling )

[vtsteam]

Ahh, click! The fact that it isn't a sight itself and is removed solves all the questions I had re robustness, the measurement increments, why vernier, and wouldn't it block the view.

It is a removable adjusting tool. All of those then are answered. But also as a tool for setting sights, it does relate to weaponry and angular measurement, as Rob said early on.

[Arbalist]

Joe's link is pretty conclusive. I'm surprised though as it doesn't look robust enough and even looks bent in the first picture.

[S. Heslop]

Found it!  This thing is a ventometer, used for adjusting military rifle sights

http://www.militaryrifles.com/britain/MHVentometer.htm

If you decide you don't need it, let me know

Cheers, Joe

(edited for crap spelling )

Thank god! This has been haunting me.

[vtsteam]

Joe's link is pretty conclusive. I'm surprised though as it doesn't look robust enough and even looks bent in the first picture.

I'm guessing it was originally kept in a case and used for calibration, not active battle use. It would be pretty clumsy and slow for that. So robustness not an issue. It's basically a caliper.

Maybe this one, ex-service, was tossed in a drawer somewhere and got bent.

[steampunkpete]

Well done Joe - champion WWW searching.

I had tried for hours and not found it.

I have to say that I feel pretty smug that functionally it is exactly what I deduced, except that I had thought it for artillery (father being RA) than for small arms. Now I know where to start I can do some more research on it.

Thank you very much Joe, and all the other contributors.

[steampunkpete]

Further info:

Made by a company called "Allison-Gregory" or "Gregory-Allison" depending on source.

This one is for fine sight adjustment in the horizontal plane, and is associated with setting up the sight for windage. I have found an antique gun dealer who sells Ventometers, and has a few examples of this exact model. One in good condition, as mine is, sells for £65, so it isn't entirely without value.

The ventometers that work in the vertical plane are of a different design.

[Joe d]

Pete:

Wish I could claim amazing Google-Fu powers, but as is much more normal for me, found it when I was
looking for something else!

But, at least now you know

Cheers, Joe