Ventometer by A.J.Parker
Ventometer by A.J.Parker. A ventometer that looks like it was by A.J.Parker. The name stamp on the rear is very faint!
A ventometer used for making minute adjustments on the rear sight of a Martini or Long Lee Enfield rifle. Gauge used in gun manufacture.
The ventometer has a cut out that would fit across the mount of the sight.
The blade sticking proud of it is micro-adjustable and would lay across the actual rear sight notch.
If you were shooting to one side of your target, you would line up the blade with the centre of the v-notch, then adjust it one mark in the correct direction, then use a pencil to mark the rear sight and use that mark as the rear sight, and so-on until you were shooting centre.