Help identify an Alex MArtin (Glasgow) ladder sight

[hjohnso4]

Hello All - Can anyone help to identify this Alex Martin ladder sight? I suspect it may be one part of an aperature sight set. Thank you

[tiriaq]

I believe that is a sight adjusting tool, for setting precise elevations.

[Alan de Enfield]

It is not a sight part, it is a tool that is used during assembly - I think it is something like a venier to get the sight level / square.

Somewhere I have details and pictures but I cannot find them at the moment. I'll keep looking.

[Strangely Brown]

Ventometer is the word you're all looking for!

[Alan de Enfield]

That's the beastie ........................


https://www.milsurps.com/showthread.php?t=14692

[hjohnso4]

Of interest:

The book of the rifle
By Thomas Francis Fremantle

There are small instruments commonly known as ventometers (fig. 79) (a misleading name, as they do not in any sense measure the wind, but only assist in applying a correction for it), which are used to mark the wind line accurately on the straight bar. These are of various patterns, but all depend upon the same principle. They are placed transversely to the back sight, and bearing upon the outside of the uprights. By moving a screw, a small, sliding square is brought either to the centre of the bar, or to any other point, and enables a line to be marked in precisely the right place, the distance being measured by a little scale, similar to that of the vernier, and giving similar divisions of f^ of an inch. These are very useful little instruments, and are used by a large number of shooting men. They are sometimes fitted to the elevation vernier itself....

Does anyone know the rarity or value of these? I've been looking high and low for another example or image of an Alex Martin variety, with no luck.

[Alan de Enfield]

I've been looking high and low for another example or image of an Alex Martin variety, with no luck.

They are found for sale reasonably regularly.

Below are examples of the JH Steward and Alex Martin Versions (there were several manufacturers)

JH steward made a wide variety of complex sights and accessories - a brief history of the company :

J H Steward Limited
Opticians and scientific instrument makers
James Henry Steward (1817–1896) established J.H. Steward in London in 1852. As “Head Optician”. J.H Steward became incorporated as J.H. Steward Limited on 1st February, 1913. The company produced a large range of items for military use and advertised in their catalogues that they produced instruments for ‘Reconnoitring, Sketching, Night Marching, Signally, Gun Laying’. They were well thought of with their work to such a standard that they were opticians to ‘The British & Foreign Governments, the National Rifle Associations of England, India, Canada & the Colonies and the National Artillery Association.
They traded from the following locations:
1856 - 1971 406, The Strand – London W.C. 2
1866 - +/-1893 54, Cornhill – London E.C. 3
1867 - +/-1930 63, St. Paul’s Churchyard – London E.C. 4
1869 - +/-1930 66, The Strand – London W.C. 2
1886 - 1928 457, West Strand – London W.C. 2
1893 - +/-1905 7, Gracechurch Street – London E.C 3
1971 – 1973 Catherine Street – London W.C. 2
(just around the corner from 406, The Strand)
1973 - 1975 154, Church Road, Hove, Sussex
The family business was passed on solely through the male line. In 1971, after selling the head office they moved all the remaining stock and long serving staff member, George Goble (c. 1916-1975), around the corner to rented premises in Catherine Street. George, a dispensing optician, was now the only member of staff – running the shop but mainly retained to provide a service to long-standing customers and to reduce the stock levels. Then the remaining instrument part of the business finally moved out of London to Hove, Sussex in 1973. In 1975, despite the efforts of the founder’s great-grandson and his wife, the business closed its doors for the last time.

They manufactured the aperture / eyepiece that I have on the PH5A sight on my SMLE, It has coloured filters and a variable aperture eyepiece (like a camera)