Some ruler stuff..

[Jos L C]

Posted for member Viscount..

Opinions please ,what is it..?

Jos.

[Jos L C]

..

[Jos L C]

.,

[Jos L C]

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[afrika]

These are the set of protractors and grid scales that were used in conjunction with maps etc. Used to plot direction in mils and to make accurate gridsquare readings. The string in the middle of the protractor would be stretched to where the destination was, after placing the strings base or centre on your position. The direction could then be read from the scale side where the string crossed it. You had to line up the side on the northing or easting lines on the map depending on the way the scale was printed on the protractor. THEN you have to convert the maps grid bearing to magnetic bearing by subtracting the magnetic variation that would be printed on the map, . NOW you can use the new bearing in conjuction with your march compass (uses magnetic bearings)to get to where you want to go ! Confused ?
Very nice set too. They were usually kept in the mapcase. I have been looking for a complete set of these for a while, so well done on the find !

Hope this helps,
Steve

[J.von Canon]

My guess(?) is that it's for a "mortar fan"(ranges)observer/fire control.
Nice.

[afrika]

Yep, I think thats what the white piece is, the other larger clear one is definately a protractor.

[Viscount]

Thanks to all of you for you help
These items have been a mystery to me for some time. A great team effort !!

Regards,
Bob

[J.von Canon]

mortar fan

Mortar fan protractor & etc.
This would likely be for a heavy mortar section.
The "base gun" would be represented as the central "shoot from" point;other guns would take fire commands from azimuths taken from the base gun(think that's right-it's been awhile.)

[Johnnie]

Basically correct. The base gun would be plotted on the board, and the additional guns plotted at whatever distance they were from the base gun. Once the section was laid in using a compass or an aiming circle, and registered, the section could fire together from the base guns data, or each gun could fire it's own seperate mission, the data being plotted from it's position on the ploting board. Nice looking equipment. Probably pretty rare.
Regards,
Johnnie