Four-Point Compasses

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	|strumentiesistenti=		|strumentiesistenti=
		+	- Museo Galileo, Institute and Museum of the History of Science, Florence <br>
		+	[http://catalogue.museogalileo.it/object/FourpointProportionalCompasses.html Florence, Museo Galileo. Istituto di Storia della Scienza, inv. 3567] <br />
-	|link=
-	|immagini= <gallery widths=230 heights=368 perrow=3>
-	Image:	+	|link=
-	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 />	+
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-	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 />	+
-	</gallery>	+	|immagini=
	|autore_scheda= Filippo Camerota		|autore_scheda= Filippo Camerota

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Current revision as of 14:09, 7 September 2010

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.

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Existing Instruments

- Museo Galileo, Institute and Museum of the History of Science, Florence
Florence, Museo Galileo. Istituto di Storia della Scienza, inv. 3567

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Author of the entry: Filippo Camerota