What is function of this Zeiss Ktm/C4?

[Mikedenmark]

Yesterday, I had an idea. It might have to do with aligning barrels on double barrelled cannon mounts? Then you would insert Ziellinienprüfers in each barrel, and then use the KtM to ensure they were aligned as wished. Earlier on there was a thread here on WA on such a device for luftwaffe airplane cannons.
http://dev.wehrmacht-awards.com/foru...t=cannon+sight
Some of these Ziellinienprüfers used light, and if you put one in each barrel of this:



Then you might use the KtM to align the barrels. That would explain the shady filters.

Without an amber filter, I think it must be for adjustments of something, unrelated to the sun.

Again, just another suggestion.

[zeissasembi]

An example of a ziellinienprufer

[cannonmn]

A possibility-in celestial navigation, one's Longitude can be found using the altitude of a star near the eastern or western horizons, and the time. Maybe the device was used for that. The U-boats in particular would want to have current longitude because they would be steaming east and west or nearly so much of the time in order to chase or intercept convoys. Latitude was simple, taking the altitude of Polaris with a sextant.

[cannonmn]

Thanks for the information on gun battery alignment and bore sights. I would certainly move such use up in likelihood if my machine had any kind of fitting or surface that looked like it was made to fit accurately into a gun bore, but such is lacking.

I think another consideration would be the units, the smallest marked on the Ktm scale is one minute of angle. That's equal to 0.296 mils in the 6400 mil circle. I'd think for battery alignment we'd want to be working with tenths of mils if not smaller units. In any case, wouldn't the Kriegsmarine use mils as the unit of angular measure in fire control and battery alignment? I really don't know.

[cannonmn]

A reply from Brad on the sextant forum:

Hello John

The +/-2° measuring range, and the fact that the angle is taken between objects 180° apart speaks to a very specific celestial navigation device.

It could be dip meter. The dip of the horizon is normally assumed in celestial navigation. However, the assumed dip can often be wrong, as a function of abnormal refraction.

With a dip meter, one aligns the horizons 180° apart and measures the dip. This accounts for eye height and existing refraction. The measured value is divided by two to obtain the dip to one horizon.

The measured dip is then substituted for assumed dip, yield a more precise reduction of the calculated angle from the observed angle of the sextant.

I have no knowledge of what your device is, only what it 'could be', as the specifics described by you correspond to that detailed herein. This may be just a coincidence.

Brad

[cannonmn]

Article on a Russian naval dip meter, which could have to been inspired by one the Soviet Army captured in Jena. It looks different but functions very similarly.

https://sextantbook.com/?s=Russian+naval+dip+meter

[cannonmn]

So we can guess that the last two words in whatever Ktm stands for in the German compound word are tauschen (dip) and messer (meter.) What do you think the K represents?

[Binoswede]

Thank you all for an interesting diskussion.
I don't know "the sextant forum" and as it seams google neither.
Can you give a link?

[cannonmn]

Yes, they use the name NavList, sorry for confusion

http://fer3.com/arc/

What do you think the K in Ktm stands for? Even with the German obsession for creating long, compound words I doubt the first part would be "Kriegsmarine."

[cannonmn]

Gents,

I believe this to be a Koincidenztelemeter, "Ktm" is the usual abbreviation. It can be found on some 3 and 4 meter basis Em's, but these measure distances, no angles. It superimposes two pictures, thereby allowing to measure an angle to the horizontal. The purpose of the instrument: I don't have a clue. Might have the same function as a Torpedoauswanderungsmesser but ment for use on smaller ships?

I asked about what the K stands for in Ktm. and looking at Le Breton's post here gives the answer. I think Ktm. Is an abbreviation for Koincidenztauschenmesser (no wonder Zeiss used the abbreviation.)

Would someone remind me of the time span when the device was made based on the markings? What's the earliest date based on the use of eagle and swastika, and the latest date based on lack of manufacturer 3-letter code?

[cannonmn]

Wolfgang from the NavList forum came up with the correct name for the device. That let me find a much earlier Zeiss instrument, perhaps the very first design.

Kimmtiefenmesser

http://collections.rmg.co.uk/collect...cts/43306.html

[Mikedenmark]

Hail to you. Truly!!!
It has been an interesting thread.