Surveying Instrument Collection
Maker |
Troughton & Simms, London |
Model |
N/A |
Serial Number |
N/A |
Dimensions |
Length 850mm, Diameter of base 120mm |
Image |
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Description |
This Eidograph is an mechanical plotting instrument used to redraw maps at a smaller or larger scale. It has the same function as a pantograph. It is a brass structure consisting of a round base 120 mm in diameter and a horizontal scale bar rests on the top of the base which may be adjusted to the required scale. There is a graduated disk located at each end of the bar allowing for smooth well-defined lines to be transferred to the other map. One of these disks feature a guiding pin which is to be guided along the lines on the map to be copied, and the other holds the plotting pin which plots the map at the new scale. Both ends of the scale bar are connected to each other via an enclosed string which acts like a 'pulley system'. When a line is traced from the original map with the guiding pin, this exact line is transferred via the disks and the string to the copied map by the plotting pin at either the same or different scales. |
History & comments |
The Eidograph was designed and published by an Edinburgh professor of mathematics, William Wallace. For reference see: "Account of the Invention of the pantograph and a description of the eidograph, a copying instrument invented by William Wallace". Trans. of the Royal Society of Edinburgh 13 (1836), pp. 418-439 Simpson, A. D. C. 1991. 'An Edinburgh intrigue: Brewster's Society of Arts and the pantograph dispute', The Book of the Old Edingurgh Club, 1(1991), 47-73 Stanleys, W. F. "Mathematical Instruments" |
Conservation |
Stored in a large wooden box (as seen in image) |
Condition |
Good |
Remarks |
|
Dates |
Manufactured in 1880 (approx). Catalogued in 1997 & 2005 |