This slide rule is from the collection of calculating instruments assembled by Associate Professor Allan Bromley. His collection provides examples of most forms of calculating devices made from the 18th to the late 20th centuries. Slide rules form a substantial proportion of this collection.

Over the 19th and much of the 20th centuries the slide rule was the primary instrument for calculation used by many people engaged in the trades and in engineering. Although originally invented in the 17th century, and widely used for gauging (or estimating the quantities of certain products such as alcoholic spirits for the Excise) it took until around 1850 for the slide rule to become generally popular.

Specialist slide rules of many kinds were developed over the period of their use. This slide rule is a specialist rule for calculating varous factros required in sighting a field gun, probably a mortar. It is of German Army World War II issue.

Artillery slide rule with pouch, plastic / leather, maker unknown, Germany, 1943

Slide rule, German artillery, closed frame, wide, single-sided, double-sided slide, wide with extra wide metal framed plastic cursor - plastic / metal. In leather holster. Unknown maker. 1943

German military slide rule. Bromley suggests probably for use with a mortar.
Scales are in black green and red. Instructions in tables on reverse.
In finely made, sown black leather holster with "g w r" stamped on interior of flap.

Scales:
Stock, upper:
W1 Erhohung -> Elevation
E1 Entfernung -> Range
Slide:
G1, G2 Geländewinkel -> (angle of error in landing point ??)
Slide, reverse:
G3 Geländewinkel
a fur Flugzeit Aufsatzwinkel -> (angle at top of flight parabola ??)
Stock, lower:
W2 Erhohung -> Elevation
E2 Entfernung -> Range
S Flugzeit -> time of flight

Made: 1943

Face: gwr Marz 1943 - se. Gr. W. 34 - Nur fur den Dienstgebrauch! - various scale labels.
Reverse: Inistructions for use

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1943