Corpus Agrimensorum
Another of my to-dos is a page describing the romans two primary surveying
instruments, the groma and the libra.  The groma was the instrument used by the
Romans to lay out
roads.  While the groma was restricted to laying out horizontal
dimensions, the libra complemented it with the measurement of vertical angles.  
Without this instrument, the famous Roman aqueducts, such as the
Pont du Gard,
would of been impossible to build. I hope to be able to include some detailed drawings
showing their possible contruction, to the end of being able to fabricate usable
instruments.  There exist many references, but unforunately details of the actual
construction and dimensions of both the groma and the libra are scarce.  Some
guessing may be necessary.

Here are the first set of
my drawings for the groma.  Other than the gross dimensions
of the width and height, the dimensions that I've used are guesses.  And more to the
point, I have yet to attempt to build a groma based upon these drawings.  This is all
very preliminary.