Click on a cover picture for a larger version.
The front cover of A Treatise of Mathematical Instruments features a variable width drawing pen, an ivory plain scale, a set of brass dividers, an ivory sector, and a brass bows. The photograph was taken by and is copyright 2001 by David Manthey.
With the exception of the sector, all of the instruments come from a mid nineteenth century set of drafting instruments. Although these are from a later time period that A Treatise of Mathematical Instruments, they are almost identical to the drawings of the instruments on the title plate.
The sector is most likely from the 1810s, though it may be from the 1790s. It was made by the Blunt company in London (not to be confused with the instrument makers of the same name in the northeastern United States). The sector is very similar to the one described in the text, except that it lacks the line of versed sines.
The back cover shows an ivory parallel ruler, a pair of proportional compasses, and a pair of compasses with a variety of optional points. These points, from left to right, are a leg extender, a divider point, and a variable width pen point.
These instruments are from the same set of drafting instruments that appear on the front cover. All of the instruments and the sector are in the collection of David Manthey.
All of the instruments still work, though the points of the dividers are somewhat bent and need sharpening, and the proportional compasses are a bit stiff.
A Treatise of Mathematical Instruments · by John Robertson ·
with Notes by David Manthey
ISBN 1-931468-11-7 · Copyright © 2002 by David Manthey · 6x9", 284 pages.
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