Geometrical Gunnery Instrument by Zorn
date: label: date made
content: ca1620
name: label: maker
content: Zorn, Georg
notes: label: Description
content: This brass gunnery instrument has two rectangular legs with pointed tips that are held together at one end. At this end they are also joined to a shorter central leg that has a flat brass ring at its end. Supports from the two outer legs to the central leg assure that they remain symmetrically placed as they are opened. There are pins to hold something in the middle of the disc at the end of the central leg, but this is missing. One side of the instrument has a scale that runs from 0 to 975 along one outer leg and then from 1000 to 2000 along the other (i.e. if the legs are separated to 180 degrees, they form a scale of equal parts 2000 units long, divided to five units). The central leg has a scale marked K that runs from 0 to 180 and indicates the angular separation of the outer legs. It also has a scale marked P that runs from 15 to 3 and indicates the number of sides of regular polygon that has the corresponding vertex angle (e.g. when the angular separation is 90 degrees, this scale reads 4). Between these two scales is a very short scale marked "H" that runs from 10 to 160. There also is a scale of degrees around the ring that is marked at 30 degree intervals and divided to 10 degrees. There are two holes in the central leg, fairly near the pivot point.
label: Description
content: On the reverse side of the instrument, each of the outer legs has a scale that runs from 0 near the pivot to 1000 near the tip, divided to units of 25. The ends of the scale near the tips are marked C and B and the pivot is marked A. The central leg has three short scales. One is labeled P and runs from 1 to 24, the central one is labeled N and marked at 10, 20 and 90, and the third is labeled T and runs from 10 to 180.
label: Description
content: Compare the instrument with plates from the work of Leonhard Zubler cited below.
label: Description
content: References:
label: Description
content: Leonhard Zubler, <I>Nova geometrica pyrobolia. Neuwe geometrische Büchsenmeisterery : Das ist: Grundtlicher Bericht, wie man durch ein neüw Geometrisch Instrument mit sonderer behendigkeit jedes Geschütz klein oder groß, bey tag oder nacht nit allein richten, sonder zugleych auch desselben höhe vnd weite messen sol ; Mit schönen kunstreychen Kupfferstucken geziert vnd an jetzo erstlich allen Kunstliebenden, sonderlich aber Zeüg- vnd Büchsenmeisteren zu gutem an tag geben </I>. The German part of the title can be translated: Basic report on how to judge each artillery small or large, by day or night alone, by means of a new geometric instrument, with special detachment, but also to measure the same height and distance; First of all adorned with fine art-fairy pieces of copper, and now for the good of all art-lovers, but especially for novices and gunmen (Zurich, 1608).
label: Description
content: The ”Geometry and War” website of the Oxford Museum of the History of Science at http://www.mhs.ox.ac.uk/geometry/cat13.htm. This includes images of several plates from Zubler. There also is a similar instrument in the Oxford collections.
label: Location
content: Currently not on view
place: label: place made
content: Germany: Bavaria, Augsburg
topic: label: Subject
content: Mathematics
setName: label: See more items in
content: Medicine and Science: Mathematics
label: See more items in
content: Military
dataSource: label: Data Source
content: National Museum of American History
identifier: label: ID Number
content: MA.322760
label: catalog number
content: 322760
label: accession number
content: 248674
objectType: label: Object Name
content: geometrical gunnery instrument
physicalDescription: label: Measurements
content: overall: 1.8 cm x 5.5 cm x 43.3 cm; 23/32 in x 2 5/32 in x 17 1/16 in