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

[James Landau]

I posted this query on the Historia Matematica mailing list and got two
responses so far:

    *****   response  1  *****

undoubtedly Stephen Greenleaf is referring to a "porta crayon", an early
kind of mechanical pencil. A nice specimen from the 1680s is on display at

http://jas-townsend.com/product_info.php?cPath=27&products_id=382.

Googling will help you to find a lot more examples.

Eisso
========================================
Eisso J. Atzema, Ph.D.
Department of Mathematics & Statistics
University of Maine
Orono, ME 04469
Tel.: (207) 581-3928 (office)
(207) 866-3871 (home)
Fax.: (207) 581-3902
E-mail: atzema at math.umaine.edu
========================================

  *******  response 2  *********

Possibly the "g" is a misprint for "c"; very probably
the object is a porte-crayon. The Oxford English Dictionary
defines this as

"An instrument used to hold a crayon for drawing; usually a
metal tube split at the end and held by a sliding ring so
as to grasp the crayon."

The earliest English citation there (1720) is this:

"Black Lead in the Lump..used in an Instrument..called a Porto-Crion."


William C. Waterhouse
wcw at math.psu.edu
Penn State

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