Monday, 9 March 2009

Very strange instrument in Peter Delehar's Shop

Peter Delehar started the Scientific Instrument Fair in London 24 years ago and has enthusiastically dealt in esoteric and interesting instruments in the same shop his father started 90 years ago this year.Peter has a reputation for exhaustive research on most of his pieces and this one is no exception:here's what he has to say about it:This rare, unusual instrument, is made of glazed paper on card and is contained in its original marbled card slip case. It is entirely covered, on both sides, including the edges, with tables, gauge points and an arc for use as a clinometer. It was invented in 1852 by Maximilion Robert Pressler (1815-1886), the father of the modern science of forestry.
It is signed *PRESSLER’S INGENIEUR-MESSKNECHT Tharand. Dresden*. The scales include those titled ‘*Reciproken*’, ‘*Bogen*’, ‘*Kreis*’, ‘*Qw*’, ‘C*w*’, ‘*Centi*’, ‘*Tg*’, etc. and many conversion factors.

To use this as a clinometer the flaps are folded over each other (they are not the same length to allow for the thickness of the card) and it is placed on a post or held in the hand. The plummet (bob missing) indicated the angled observed with the missing, loose sight.

A remarkable, perhaps even unique survival. Width, when laid flat, 8.6 inches (21.8cms). the condition of the slip case is good but noting that there is some wear on one corner. The condition of the instrument is is also good, but also noting that the hinges are slightly frail, the plummet and sight are missing
and there is slight discolouration of the paper.

See: R. Max. Pressler, /MathematischeBrieftasche mit Ingenieur-Messknecht, Dresden 1860/.
M.R. Pressler, /Der Messknecht als Mastknecht, Braunsweig 1853/.
/Zur Verwandlung der Messknechtstafel in das Visirinstrument. N.D. (1860?)/

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