Striking 19th Century Geometric Perspective Pair of Diagrams in Ultra Black Ink

This one came out of a large c. 1870s century folio filled with all sorts of things, including a whole notebook of geometric perspective drawings, listed separately, and an assortment of handwritten notes on everything from wax flower making to casting. Included were a handful of single page/loose perspective drawings, executed in black ink, which I think so good on their own I am listing individually--this one to my eye just a stunner, showing the construction of perspective as applied to the rendering of a tessellated surface--looking very much like a gameboard! 

12 1/2" x 7 5/8". Black ink on wove. Scattered foxing/toning spots as evident, and rough bottom edge, easily trimmed.