Four-Point Compasses
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| + | Name currently used for the [[Reduction Compasses | reduction compasses]]. | ||
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| + | Also called [[Double Compasses | double compasses]] or "compass with double points" (Muzio Oddi, ''Fabbrica et uso del compasso polimetro'' [Construction and operation of the polymeter compass] Milan 1633, introduction), the instrument was used as a [[Proportional Compasses | proportional compasses]], for measuring simple proportional ratios, or as a [[Reduction Compasses | reduction compasses]] to enlarge or reduce drawings. The compass was composed of two intersecting legs with points on all ends and a fixed or variable pivot depending on the proportional ratios desired. Ancient examples of this instrument have been found in the excavations of Pompeii. | ||
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| - | + | Unavailable image | Nicolas Bion. ''Traité de la construction et des principaux usages des instruments de mathematique : avec les figures necessaires pour l'intelligence de ce Traité'', Paris, 1725, tav. VIII p.70, particolare.<br /> | |
| - | + | Unavailable image | George Adams. ''Geometrical and graphical essays, containing a general description of the mathematical instruments used in geometry, civil and military surveying, levelling and perspective : with many new practical problems''. London, 1813., tav. I, particolare.<br /> | |
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Revision as of 08:48, 13 November 2009
Name currently used for the reduction compasses.
Description
Also called double compasses or "compass with double points" (Muzio Oddi, Fabbrica et uso del compasso polimetro [Construction and operation of the polymeter compass] Milan 1633, introduction), the instrument was used as a proportional compasses, for measuring simple proportional ratios, or as a reduction compasses to enlarge or reduce drawings. The compass was composed of two intersecting legs with points on all ends and a fixed or variable pivot depending on the proportional ratios desired. Ancient examples of this instrument have been found in the excavations of Pompeii.
Images
Unavailable image
Nicolas Bion. Traité de la construction et des principaux usages des instruments de mathematique : avec les figures necessaires pour l'intelligence de ce Traité, Paris, 1725, tav. VIII p.70, particolare. |
Unavailable image
George Adams. Geometrical and graphical essays, containing a general description of the mathematical instruments used in geometry, civil and military surveying, levelling and perspective : with many new practical problems. London, 1813., tav. I, particolare. |
Author of the entry: Filippo Camerota
