View Full Version : What is this thing, how is it used?

01-30-2008, 05:22 PM
A friend of mine sent me this picture http://mysite.verizon.net/stockerwellcome/anglevernier.jpg and asked me what the heck it was, how/why was/is it used, and in particular, how does the vernier work. I await your wisdom....

01-30-2008, 05:26 PM
its for a big gun...the sort thats mounted on wheels

its used for getting the angles set

got one myself

all the best..markj

Peter Neill
01-30-2008, 05:31 PM
Also known as a Clinometer.


01-30-2008, 05:32 PM
Even on Machine guns....

Often called a Gunners Quadrant..

Here is some good info:


01-30-2008, 05:39 PM

01-30-2008, 06:16 PM
You guys are amazing.

Any insight as to how the vernier works? It's +/- 25, which is +/- one notch on the angle...but how does sliding the vernier left or right adjust anything?

Thomas Staubo
01-30-2008, 06:38 PM
but how does sliding the vernier left or right adjust anything?

'The level holder slides along the curved top surface of the radial arm'

As it says in the link, the top of the radial arm is curved. And when the level is moved along this curve, the angle changes slightly.


01-30-2008, 07:04 PM
Thanks - I missed that.

Your Old Dog
01-30-2008, 07:11 PM
Is it safe to say it acts similar to a macninist vernior only for angles?:confused:

01-30-2008, 07:54 PM
On mortars we used to set the angle and crank until the bubble was centered and level. It was then ready to fire. We were told we were expendable but that mortar sight was not.

01-30-2008, 08:33 PM
Even on Machine guns....

Often called a Gunners Quadrant..

Here is some good info:


Thanks Bguns.

A very interesting post.

The theory and application of "mil" as applied to the military applications are quite interesting.

See the following:

A bit more info on the many uses and applications of inclinometers generally is at:

And yes, I do have a back-ground in military (Naval) guns.

Surveying too.

Optics Curmudgeon
01-30-2008, 08:40 PM
That one's from some foreign army, here's a picture of the US version.


01-30-2008, 10:20 PM
The inclinometers shown are calibrated in "mil" - as previously.

They are effectively an initial range-setting device.

Once the target distance (range) in known, the ballistics tables for the particular weapon and ammunition are consulted to find the gun elevation required in mil units.

That is the reason for the spirit level - to set the gun relative to a known zero/horizontal reference.


Each gun has its own (in)clinometer which has been set up for/to/on that gun.

Once the gun starts firing the aimer uses his vision to determine corrections from the fall of shot for elevation (range) and deflection (left/right).

Unless the tribrach on which the gun rotates laterally is very well set up, any errors will negate the range elevation zero at any other bearing.

Needless to say, with all the crashing and banging about that the gun gets during firing, it pretty well cancels out further use of the inclinometer.

While, in theory, the mil units can be used to set range, the ballistics of the gun and ammunition will require further additional elevation (sometimes called "super-elevation" and other times called "tangent elevation") - as well as "drift".

But a good Gunner can estimate range, elevation and drift as can a good rifle-man and adjust accordingly.

Now-a-days, "tracer" rounds are included in clips of ammunition to indicate where the fall of shot is.

"Spotters" (people) are really excellent here.

I suspect that the clinometers would not have got a lot of use when "things got hot".

Paul Alciatore
01-30-2008, 10:45 PM
I was on active duty in the US Army for 3 years, Ordnamce Corps and for about 12 more years in the reserves. One of the 3 years of active duty was in Vietnam. Lots of guns of all sizes up to 6 inch/155mm. Frankly, I never saw one of those in use or even in storage. The smaller guns, as in those carried by one man, didn't need it. You aimed and fired or you sprayed with the machine guns. Snipers had scopes. The artillery guns had removable optical "sights" that were a lot more accurate than a gunner's quadrant. These were carefully carried in their own cases and never left on the gun when it was fired. These optical sights were used in conjunction with aiming stakes, not the targets which were completely out of sight.

I suspect they are a leftover from the 19th or earlier centuries. Can you say "Civil War"? Today I am sure the aiming technology involves computers and global positioning.

Optics Curmudgeon
01-30-2008, 11:27 PM
Until the late 1950's every artillery piece was supplied with one, a leftover from an earlier era, as you have said. I have never met an artillerist, of any era, that actually used one. Each gun had a flat machined on the breech end parallel with the bore, to place the quadrant on. Probably on the orders of some general that actually remembered using one, back when. The one in the picture has a 7 digit stock number, which makes it pre 1958. I've never seen one newer.


01-30-2008, 11:37 PM
These things were/are used to "aim" machineguns for "plunging fire" from the relative safety of your trench to their trench or in a "reverse slope" defense.
You have no line of sight to a target, just a direction and distance to "lay" the guns to, and when you got the word, you "rained lead" (finial protective fire) and hopefully they ran out of people before you ran out of bullets. With all weapons (and no weapon is ever obsolete), terrain dictates tactics. The Great War and Korea would have used this tactic more than Vietnam. The "Modern War" peanut gallery doesn't like the idea of "to whom it may concern" targeting, somebody might get hurt...

01-31-2008, 03:07 AM
For example when tanks are called in for indirect long range fire (Seldom but...)

Tanks are on a ramp to get more gun elevation (Tank sights not much use without capability to add the extra semi precise elevation to firing calculations)

Seldom needed, but fairly cheap and handy when things get really off level...

With Modern Ballistic computers a bit old fashioned, but no electricity required..

My experiance was repair/maint on M60A1 tanks, M109A1 155s, 4.2 and 81mm Mortars, and the good ol M110 8 inch gun :) old school stuff, some with backup manual firing devices to be able to shoot even when power was out...

The Mechanical Ballistic computers were a neat bunch of gears,cams, driveshafts,(for Super elevation) and handles... add in the fairly simple gyrostabilzation systems, fairly wide spaced lens (triangle based) optical rangefinders, and you could do a pretty good job on the range..