Original Item. Only One Available. This is an original German WWII Deckungswinkelmesser, a compact folding military instrument used to measure vertical angles for indirect fire and terrain surveying. Manufactured by J.D. Möller G.m.b.H. of Wedel, Germany, the instrument was designed to determine the Deckungswinkel, or angle of cover, between a firing position and intervening terrain. Such measurements were particularly important for artillery and heavy machine guns operating from concealed positions.

The instrument is constructed primarily from black-painted metal, with a hinged rectangular body, folding sighting assembly, and graduated measuring arm. A small viewing aperture allows the operator to observe a terrain feature and read the corresponding angular graduation simultaneously. The measuring arm also incorporates a linear scale, with its original numbered graduations remaining clearly legible.

One side bears the original manufacturer's and military markings:

dhq
H/6400
128607

The wartime manufacturer code dhq identifies J.D. Möller G.m.b.H. of Wedel, Holstein, a German manufacturer of optical and precision instruments. The H/6400 designation refers to the military angular measurement system based on 6,400 Strich per complete circle, while 128607 is the instrument's serial number.

A particularly interesting feature is the original German instruction plate, secured to the body with four slotted screws. It reads:

Halte knieend Deckungswinkelmesser
vor ein Auge, daß Deckung und Teilstrichzahl
gleichzeitig zu lesen sind.
Lies Teilstrichzahl ab.
Strichabstand = 5/6400

"While kneeling, hold the Deckungswinkelmesser before one eye so that the obstruction and the graduation number can be seen simultaneously. Read off the graduation number. Graduation interval = 5/6400."

The instrument remains in very good overall condition, retaining much of its original black finish and clearly legible markings. There is scattered edge wear, minor oxidation, and localized finish loss from age and handling. The instruction plate exhibits light scratches and surface discoloration, while the hinged components and sighting assembly remain present. The instrument has not been tested for measurement accuracy or calibration.

Historical Context

The Deckungswinkelmesser, literally "cover-angle meter," was a specialized measuring instrument used by the German armed forces during WWII. Contemporary English-language military terminology identified it as a site-to-mask clinometer, referring to its function in measuring the angular height of an obstruction, or "mask," above a firing position.

In indirect-fire operations, artillery crews frequently positioned their guns behind hills, embankments, buildings, or other natural and artificial cover. These concealed positions offered protection from enemy observation and direct fire, but required careful calculation to ensure that projectiles would clear the intervening obstacles. The Deckungswinkel was an important element in determining the minimum elevation necessary for a safe trajectory.

The instrument provided a straightforward method of obtaining this measurement. Following the prescribed procedure, the operator knelt and held the opened device before one eye. By aligning the upper edge of the obstruction with the internal graduated reference, he could read the vertical angle directly. The resulting measurement could then be incorporated into the firing calculations.

The viewing arrangement was particularly practical for field use. The operator could observe both the relevant terrain feature and the numerical graduation at the same time, allowing a reading to be taken quickly from the firing position. Its folding construction also made the instrument convenient to transport with other surveying and fire-control equipment.

German military gunnery used the Strich system for angular measurement, dividing a complete circle into 6,400 units. Each Strich represented 1/6400 of a circle, approximately 0.05625 degrees. This system was useful for estimating angles, distances, and lateral corrections during military surveying and fire direction. The Deckungswinkelmesser's graduations were spaced at intervals of five Strich, equivalent to approximately 0.28125 degrees.

Although particularly relevant to artillery, the Deckungswinkelmesser was also used in connection with heavy machine-gun operations. German doctrine provided for the employment of machine guns in indirect fire from covered positions, where crews relied upon calculated elevations and directions rather than direct observation of the target through the weapon's sights. Determining the angle of intervening cover was an essential part of preparing these positions.

The instrument was included in the German Army's official equipment regulations, specifically H.Dv. 448/6, Beobachtungs- und Vermessungsgerät, Heft 6, originally issued on September 5, 1932, and subsequently revised and reprinted in 1939. This regulation covered military angle measurers, Deckungswinkelmesser, map angle measurers, position-measuring equipment, mountain angle instruments, and compasses. Its inclusion demonstrates the established place of the instrument within German field surveying and fire-control equipment before and during WWII.