William Oughtred published his design for a slide rule in 1632. A series of designs followed. In 1727 Jacob Leupold published the "Theatrum Arithmetico-Geometricum"[^A scanned version of this book may be downloaded from http://ia600304.us.archive.org/33/items/theatrumarithmet00leup/theatrumarithmet00leup.pdf (viewed 3 Jan 2012)^] of which Table XII (page 241) is held in this collection (see below).[^This page was held in a German family and placed on auction on ebay in January 2012, after the seller's grandfather, an art collector, who had held it and had it restored, passed away.^]
This page shows three existing designs for logarithmic proportional rules. The top most (titled Mechanische Rechen Kunst and bearing also the initials MLBMC of its maker) is effectively a Gunter scale and dividers would be used to perform multiplications or divisions using the scale.[^a diagram of this 
is shown at "Rechenschieber mit logarithmischen Skalen" http://www.rechenwerkzeug.de/staebe.htm (viewed 2 Jan 2012)^] The lower two are slide rules.
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