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Details
A rare early 17th-Century German brass Gunner's composite levelling instrument and gauge
This unusual instrument consists of a long bar with a triangular frame at one end, on which are mounted three levelling arcs. One of these, A, butts onto the bar at right angles, while the other two are alongside the bar, B to the left and C to the right. These levels are used with different dispositions of the instrument. All three levels are made in the same form, but differ in size and in their scales. There is a graduated arc, a curved retaining bar with a central threaded hole for a screw to lock the plummet when not in use, and a plummet consisting of an iron shaft and scale pointer, with a brass weight with five facets.
Level A has a degree scale 25°-0-25°, divided to half a degree, and numbered every five degrees. Length of plummet 52mm; suspended from apex. The foot measures 63 x 14mm, and is curved for placing on the base of an artillery piece. The curve has become bent over time, so is now nearly flat. The face plate is hinged to the foot, and is kept in the vertical position by a slot and lug at the top with a peg (missing). This plate is moved to permit the use of the other two levels. At either end of the slot is a maker's punch mark: unidentified. Such marks were used by the metal workers of Nuremberg and other craft centres (Lockner).
Level B has a non-linear scale calibrated 0-35 in quarter units. Length of plummet 72mm; suspended from the end of a short arm of the triangular frame. With the long bar as the base, this scale was used to measure a gradient: the horizontal distance equal to that along the slope less the reading on the scale.
Level C has a degree scale 0-90° numbered in tens, and divided in quarter degrees. Length of plummet 52mm. This scale could measure the angle of elevation, with the long bar pointing in the direction of sight (vanes may have been fitted). Below the quadrant arc, the hypoteneuse of the triangular frame carries the following lettering and numerals all of which are engraved:
WATER . PAS . 3½ . TOL
DEYRONT . ¼ 6 . TOL
AVS . DEN . HACK . 3½ 6 . TOL
The long bar measures 13in. (33cm.), and has a cross-section of 60mm. Each side is engraved with a scale, and at one end of each is the engraved outline of the base of a gun. The scale on the left side is divided into 12 TOL (inches), subdivided in quarters. This scale of 12 inches measures 294mm, which is close to some German standard measures. The next three scales relate to this length standard by means of which one can find the weight in pounds of a round shot from the measure of the diameter. The scale on the top of the bar is engraved: STEIN (stone); it is divided 0-60 in single units, numbered in tens. The scale on the right-hand side is marked: EISSER (iron); divided in units 0-128, numbered in tens. The lower scale is marked: BLEY (lead); it is divided 1-128.
The 12-inch scale is of particular interest since it may give a clue to the region where the instrument was made. The standard corresponds to some old South German measures. For example: the present gauge measures: c.294mm; Nuremburg Artillerie Fuss: 293.15mm; Augsburg Fuss 296.16mm (Doursther, p.414). The wording is in Low German. The numbers marking out the scales are stamped, and show some of the common errors, including misplaced numbers that are overstamped, or additionally stamped in the vicinity of the error. An inverted 2 substitutes for a 5. Trouble has been taken in splicing together parts of the structure. The Museum of the History of Science, Oxford, has a German gunner's gauge dated 1612 that is similar to the long bar on the present instrument, the sides marked: Schvh, Stein, Eisen, Bley (Bennett & Johnson, p.24, no.4). It is possible that the composite level is of the same date -- 13in. (33cm.) long; 3¾in. (9.4cm.) high
See Colour Illustrations
This unusual instrument consists of a long bar with a triangular frame at one end, on which are mounted three levelling arcs. One of these, A, butts onto the bar at right angles, while the other two are alongside the bar, B to the left and C to the right. These levels are used with different dispositions of the instrument. All three levels are made in the same form, but differ in size and in their scales. There is a graduated arc, a curved retaining bar with a central threaded hole for a screw to lock the plummet when not in use, and a plummet consisting of an iron shaft and scale pointer, with a brass weight with five facets.
Level A has a degree scale 25°-0-25°, divided to half a degree, and numbered every five degrees. Length of plummet 52mm; suspended from apex. The foot measures 63 x 14mm, and is curved for placing on the base of an artillery piece. The curve has become bent over time, so is now nearly flat. The face plate is hinged to the foot, and is kept in the vertical position by a slot and lug at the top with a peg (missing). This plate is moved to permit the use of the other two levels. At either end of the slot is a maker's punch mark: unidentified. Such marks were used by the metal workers of Nuremberg and other craft centres (Lockner).
Level B has a non-linear scale calibrated 0-35 in quarter units. Length of plummet 72mm; suspended from the end of a short arm of the triangular frame. With the long bar as the base, this scale was used to measure a gradient: the horizontal distance equal to that along the slope less the reading on the scale.
Level C has a degree scale 0-90° numbered in tens, and divided in quarter degrees. Length of plummet 52mm. This scale could measure the angle of elevation, with the long bar pointing in the direction of sight (vanes may have been fitted). Below the quadrant arc, the hypoteneuse of the triangular frame carries the following lettering and numerals all of which are engraved:
WATER . PAS . 3½ . TOL
DEYRONT . ¼ 6 . TOL
AVS . DEN . HACK . 3½ 6 . TOL
The long bar measures 13in. (33cm.), and has a cross-section of 60mm. Each side is engraved with a scale, and at one end of each is the engraved outline of the base of a gun. The scale on the left side is divided into 12 TOL (inches), subdivided in quarters. This scale of 12 inches measures 294mm, which is close to some German standard measures. The next three scales relate to this length standard by means of which one can find the weight in pounds of a round shot from the measure of the diameter. The scale on the top of the bar is engraved: STEIN (stone); it is divided 0-60 in single units, numbered in tens. The scale on the right-hand side is marked: EISSER (iron); divided in units 0-128, numbered in tens. The lower scale is marked: BLEY (lead); it is divided 1-128.
The 12-inch scale is of particular interest since it may give a clue to the region where the instrument was made. The standard corresponds to some old South German measures. For example: the present gauge measures: c.294mm; Nuremburg Artillerie Fuss: 293.15mm; Augsburg Fuss 296.16mm (Doursther, p.414). The wording is in Low German. The numbers marking out the scales are stamped, and show some of the common errors, including misplaced numbers that are overstamped, or additionally stamped in the vicinity of the error. An inverted 2 substitutes for a 5. Trouble has been taken in splicing together parts of the structure. The Museum of the History of Science, Oxford, has a German gunner's gauge dated 1612 that is similar to the long bar on the present instrument, the sides marked: Schvh, Stein, Eisen, Bley (Bennett & Johnson, p.24, no.4). It is possible that the composite level is of the same date -- 13in. (33cm.) long; 3¾in. (9.4cm.) high
See Colour Illustrations
Literature
BENNETT, J., & JOHNSON, S., The Geometry of War 1500-1750 (Museum of the History of Science, Oxford, 1966)
DOURSTHER, H., Dictionnaire universel des poids et mesures anciens et modernes (Brussels, 1840)
LOCKNER, H.P., Die Merkzeichen der Nrnberger Rotschmeide (Beyerisches Nationalmuseum, Munich, 1981)
DOURSTHER, H., Dictionnaire universel des poids et mesures anciens et modernes (Brussels, 1840)
LOCKNER, H.P., Die Merkzeichen der Nrnberger Rotschmeide (Beyerisches Nationalmuseum, Munich, 1981)