Professor Willis's Odontagraph by HOLTZAPFFEL - Odontograph *SOLD*
A scarce Professor Willis's brass odontagraph by HOLTZAPFFEL of London.
Also sometimes spelled 'odontograph', an instrument for setting out the teeth on gear wheels.
Marked 'PROFESSOR WILLIS'S ODONTAGRAPH MADE BY HOLTZAPFFEL & Co LONDON' on the shorter arm with 'SCALE OF CENTRES INSIDE THE PITCH CIRCLE OUTSIDE CENTRES' with the graduated scale on the other.
9 inch and 131/2 inch long arms with both being 13/8" wide.
A few minor surface scratches, please see images.
A fine example of a rare item.