The matrix engraving cutters Goudy employed were pyramidal-shaped with an unspecified number of sides and nominally flat sides (though his cutter grinder will actually produce a slightly concave surface. 
Although in Typologia Goudy indicates that he paid careful attention to cutter angles, to the best of my knowledge he did not publish the details of these angles or his cutter geometry. The divided circle he refers to in Typologia is, I believe, simply an indexing device for creating pyramidal cutters with a particular number of faces; it was not (again, so far as I can figure) used for setting the longitudinal angles of the cutters. (These longitudinal cutter angles are of great practical importance to the matrix engraver. If they are too small (giving a slender cutter), the cutter will break easily. If they are too large (giving a robust cutter), the type's beard may exceed the body of the type (producing an unwanted kern of the beard).
In Boone's article, Goudy indicates that his dimensional tolerance for matrix cutters is 0.000,2 inches (two thousandths of an inch). The article is (ironically) imprecise about whether this is a +/- tolerance or a total tolerance (thus +/- 0.000,1). 
2. See also the chapter on Goudy's microscope for a discussion of why it is that Goudy may not have been achieving the accuracy that he believed he was.
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