Q: "portagraion" -- a "mathematical instrument" circa 1745?

[Joel S. Berson]

What is a "portagraion", in the following quotation from 1745?  I've
done my best in OED2 and googling with various possible
spellings.  The mention just before of drawing pens suggests
"pantograph", but that's not close to what I see.

Stephen Greenleaf, Mathematical Instrument-Maker...;Makes and mends
all Sorts of Mathematical Instruments, as Theodolites, Spirit Levels,
Semicircles, Circumferences, and Protractors, Horizontal and
Equinoctal [sic] Sun Dials, Asimuth and Amplitude Compasses,
Elliptical and Triangular Compasses, and all Sorts of common
Compasses, drawing Pens and Portagraions...; with sundry other
Articles too tedious to mention.

Thanks,
Joel

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