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Trench Mortar sight


centurion

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Belongs to a neighbour - brought back by his grandfather said to be a German Trench Mortar Sight

comments please.

post-9885-0-61482000-1393860955_thumb.jp


post-9885-0-78380200-1393861037_thumb.jp

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Seems to have been a sighting or bearing device. Probably incomplete, the central pivot could have carried a compass card or needle and there could have been a rotatable bezel that could have been locked by the knurled screw. In other word something like a prismatic compass less prism. Can't see it as part of a mortar sight. More like a survey device.

Old Tom

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Having had another look, and perhaps cleaned my specs, the graduations although difficult to read seem to be unusual. Would you post the maximum reading please.

Old Tom

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How old is the grandfather - i.e., which war? There was a Hildebrand munitions factory in Freiburg in WWII, of ill repute, but I don't know it it was operating in WWI. If WWII vintage there should be a WaA mark

Certainly a sighting device, and the lever looks like it was intended to hold the (missing) azimuth pin in place when taking an azimuth or bearing.

But the calibration of the dial seems a bit odd. They are not Artillery mil markings are they? Or did those develop and come into use after WWI?

Trajan

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Centurion,

There is lots on the internet regarding Max Hildebrand including a Wikipedia entry. I don't have time to go through it all but it appears to me that

Old Tom is correct in that Hildebrand manufactured fine surveyors' instruments. The instrument in your photos would probably have had a glass top to

protect the compass needle, now missing but I imagine restorable.

Regards,

Michael.

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Having refreshed my memory on mils and peered again at the dial I think the calibration is in mils - 6400 to the circle. The mil was devised, I believe, around WW1 time and was not, as far as I know in military use until about WW2.

Again with a closer look Trajan is correct the knurled knob would restrain/lock the card or needle either for transit or for a reading.

Old Tom

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Having refreshed my memory on mils and peered again at the dial I think the calibration is in mils - 6400 to the circle. The mil was devised, I believe, around WW1 time and was not, as far as I know in military use until about WW2.

Again with a closer look Trajan is correct the knurled knob would restrain/lock the card or needle either for transit or for a reading.

Old Tom

I admit to a little bit of cheating (as it were) here, Old Tom... I am just right now introducing the students on my surveying course on how to use a field compass (regular and military), and differences in azimuth readings, etc., and so all these details are fresh in my mind! Yes, I know, they all have GPS (but no UTM grids!) and compasses in their wretched I-phones and the like - but as I tell them, what do you do when (not if!) the battery runs out in the middle of, say, Van Province, and you don't have a spare!

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If the sun is not out, one looks to see which side of the trees carry moss and lichen. If no trees??????

Old Tom

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If the sun is not out, one looks to see which side of the trees carry moss and lichen. If no trees??????

Old Tom

Youv'e got it! And very few trees in Van province, and even fewer less than the required century or so... Mind you, I am looking at lichen on 4,000 year old Urartian walls as a possible indicator! So far all the lichen seem to show what is older than classsical period...

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How old is the grandfather - i.e., which war? There was a Hildebrand munitions factory in Freiburg in WWII, of ill repute, but I don't know it it was operating in WWI. If WWII vintage there should be a WaA mark

Certainly a sighting device, and the lever looks like it was intended to hold the (missing) azimuth pin in place when taking an azimuth or bearing.

But the calibration of the dial seems a bit odd. They are not Artillery mil markings are they? Or did those develop and come into use after WWI?

Trajan

According to his service book he was a regular soldier from 1913 to 1934 RE until 1920 Royal Signals after that. Served in France, the Balkans and later India (has a full set of Pip Squeak and Wilfred plus an MM and IGS, NWFM) NCO most of the time. The knob unscrews and appears to have locked in place the arm that runs across to the needle in the middle. I have seen something similar on photos of minenwerfers so the idea is not without plausibility and a soldier that experienced would probably know the difference.

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According to his service book he was a regular soldier from 1913 to 1934 RE until 1920 Royal Signals after that. ...The knob unscrews and appears to have locked in place the arm that runs across to the needle in the middle. I have seen something similar on photos of minenwerfers so the idea is not without plausibility and a soldier that experienced would probably know the difference.

Ah, that adds to things! So, could have somehow been picked up post 1918... If certainly a sighting device of probably military origin. The scale on the side is in cm and mm? Germany adopted that in the late 19th century. But my gut feeling is that the lettering is all wrong for WWI period, and perfectly fine for later. As might seem to be the case for the Art.Mil calibration ('Two finger is ...' etc!). Are there no issue / serial marks on it? I think these should exist if WWI - and pretty certainly so if WWII!

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Ah, that adds to things! So, could have somehow been picked up post 1918... If certainly a sighting device of probably military origin. The scale on the side is in cm and mm? Germany adopted that in the late 19th century. But my gut feeling is that the lettering is all wrong for WWI period, and perfectly fine for later. As might seem to be the case for the Art.Mil calibration ('Two finger is ...' etc!). Are there no issue / serial marks on it? I think these should exist if WWI - and pretty certainly so if WWII!

The stuff in the box of goodies I've been given to examine is almost all WW1 vintage or related and how else would a soldier pick up a German made military object except in or just after WW1? He was in the Balkans until 1920 and then much of his service appears to have been in India

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I've been thinking about this one, first I pretty sure it is not any type of weapon sight. For starters there is no obvious mounting to attach it to a gun, mortar, whatever, and the square base with graduations makes absolutely no sense for this purpose. My next thought was that it was some form of fire control instrument, all I can say is it might be but I can't see how it would work although at first sight there may be possibilities, perhaps a combination of director and arty board, but I haven't thought these through, and it seems a complicated solution to simple problem. My final thought was that it might have been associated with a plane table.

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Well, standard field compasses these days have a graduated scale along one or more sides for use with maps, so this look like it should be used that way: i.e., get an azimuth and then get the distance. I doubt if it is for a plane table planning - I am long enough in tooth to have learned that particular art and can't remember anything like this!

On the other hand, the combination of an art.mil dial and flat base, etc., so for use with a map for artillery spotting? I have a mate who is an ex-(Dutch)army artillery spotter, so I'll see if he has any comment.

Would only add that if this is military and of WWII era, then surely there should be little eagle WaffenAmt marks on it?

Trajan

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This was bugging me so much I had to play hookie and search a bit more, and then I noticed it was FreiBERG, not FreiBURG, and found a Freiberg (Sachsen) mining compass, which led me further ... and I have almost got an exact match it! See http://www.compassmuseum.com/geo/geo_4.htm

It is indeed an Artillery compass, with 6400 MILS, reading counterclockwise. The one they show is somewhat different, and is WWI, and they state that "This compass type was built by severa (sic) manufaturers like PLATH (Hamburg) an(sic) HILDEBRAND (Freiberg/Sachsen)".

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The first question is whether German artillery used bearing or deflection laying in WW1. I have a vague idea it was the former. The basic artillery indirect fire problem is to determine a range and azimuth to the target, the easiest and most common way of doing this was to measure it on a map (or plain gridded chart), the German Army had a very good 'artillery board' for this, which was copied by UK after the war. The pre-war German Goetz sight (dial sight or panoramic telescope depending on which English dialect you speak) was the pattern for all such instruments up to the present day, although mortar sights were a bit simpler. I'm confident that the instrument in the photos is not a sight and is not a plotting instrument used on a gun position. The nearest I can think of is a sort of cheap and not very precise director (or aiming circle if that is your English dialect), but at the moment I can't work out how it would be used and it invites the obvious question 'why not just use a director?'

That leaves a map reading aid for observers, and I don't see that a counter-clockwise scale has anything to do with this. Having done the job in two wars and being an artillery instructor (12 month course) I am fortunate to know a little bit about the subject! All an observer needs is a standard compass, preferably prismatic or lensatic, a protractor and of course a map. One possibility is that German observers produced firing data, this was an option for ranged fire by UK observers in both WWs, azimuth being a switch from the zero line, or if bearing is being used a bearing. However, I can't see how the device helps with this either.

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Then what do you make of the one in the link I found? And surely the fact that these have dials in Art.Mils is indicative of military, for the use of, sighting?

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Your link says 'survey compasses'. Obviously it is designed to be placed on a flat and level surface, the only thing I can think of that fits is as I previously suggested something to do with a plane table, looks like I was probably right. I not the one asserting its a mortar sight ;-) , it's clearly not a 'sight' for mortars or artillery, and I still cannot see any other use for it in the indirect (or direct) fire process, excluding survey/map making.

Mils (I believe the Germans called them grads or something at the time) may suggest military map making/survey but I don't know enough about map making in imperial Germany, and one question would be 'what units of measurement did the various state survey organisations use?' I have a vague recollection that it was a state (ie not national) responsibility. I'd suggest that assuming the use of a 6000 unit circle means military in Imperial Germany is a bit of an assumption, and look forward to some evidence that it was so. Even being German made does not mean it was German used, Austro-Hungary come to mind.

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I can't compete with a surveyor and a gunner. However, I wonder if I was correct in suggesting that mils were not used in WW1. The site Trajan found suggests I was wrong. However Nigelfe's last post introduces a 6000 unit circle. I am getting confused.

Old Tom

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Mils (I believe the Germans called them grads or something at the time) may suggest military map making/survey ... assuming the use of a 6000 unit circle means military in Imperial Germany is a bit of an assumption...

Very good point! All I know about Mils (or grads) is that they are a useful way of giving a bearing from a position (using one finger or a span or whatever!) and knowing of their use by infantry in this way, I had simply and quite possibly wrongly assumed that they must therefore be exclusively military. Thanks!

PS: Old Tom, I know what you mean...

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France was using mils (6400) in WW1, UK was considering changing in 1914 before war broke out but stopped on the outbreak of war. Imperial Russia was using 600 circle a decade before and an even stranger unit of distance measurement, not sure where they had got to in WW1 but the 600 circle is the origin of the Warsaw Pact 6000 circle. At some point Sweden adopted the 6300 circle. I'm not sure about German and Austro-Hungary, I'm fairly sure it was 'Grads' and it may be that it was 4000 circle.

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Nigelfe

Thanks for that. So if this bit of kit was WW1 then it was used by the French.

Old Tom

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Talked with my Dutch mate (ex-professional Dutch army forward spotter in the 1970-1980's) and showed him tonight what we had. He always used field glasses with art mil readings in them and a map with co-ordinates when he was serving. He'd not seen anything like this, designed to be used on a map on flat surface, but had used the prismatic compass in his work. But after a few minutes he could see how these might be used by a forward spotter to sight in and call back where things were landing.... He was very much in favour of them being in art mil for artillery use.

BTW, I went back to the link I gave and it took me ages to find the two I was looking at, listed as WWI artillery compasses! I eventually got them by entering that web page, going back to home, and then searched for parts of the phrase "This compass type was built by severa manufaturers like PLATH (Hamburg) an HILDEBRAND (Freiberg/Sachsen)." - note the missing 'l' in several and the missing 'd' in and!

Trajan

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France also used decigrades (4000).

Before the introduction of laser rangefinders and orienting heads the normal method for 'adjusting' artillery fire (or 'ranging' in UK, etc, until 1965) throughout NATO was 'target grid corrections', the observer measured the distance of the adjusting round(s) left or right of the imaginary line from himself through the target (the 'direction', a grid bearing measured using a prismatic compass) by using the graticules in his binocular and the 'subtension rule' - 1 mil = 1 metre at 1000 metres. Having got an adjusting round onto the 'direction' he brackets the target halving the size of the bracket with each successive adjusting round. There is absolutely no place in this procedure for anti-clockwise bearings. In WW 1 UK used much the same procedure but instead of the direction ranging was on the line of fire and the actual range was adjusted, which needed a bit more skill by the observer but was faster. I don't know which the Germans used.

Where the device might be useful is for the arithmetically challenged to do a resection, ie take grid bearings to 3 or more easily identifiable points that are also on the map, then plot the back-bearings from each on the map and where they meet is the position where the bearings were measured. The device itself is well suited to use with a plane table (or even a level map-board, or a sandbag wall), but not well suited to use as a handheld compass! The device measures the back-bearings which avoids the need to addition/subtraction of 180/200/2000/3000/3200 according to the units of measurement used. Boy Scouts are taught this process, well I was. Not exactly the pinnacle of military sophistication.

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Thanks! As it was I gave my surveying class a magnetic compass practical only the other day - find a series of grid refs on the ground using a map of the main university campus, move from one point to the next, recording what's there at each point, and write down the azimuth reading between each point. You get the picture. So I walked from group to group, three in each group, watching how they did this, seeing how they went from one point to the next, then two or one of them would go back to the preceding point leaving one person as a marker to get the compass reading... It took an hour before one group realised that it was a lot easier simply to calculate the back sight (minus 180 deg.) from one spot to the other to get the relevant figure... Not exactly the brightest class I have taught...!!!

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