A C. H. Webb calculator - 'The Adder',
to the 10th March 1868 patent,
No. C671, with one large and one small readout pin-wheels, engraved with 0-99 decimal and 1-9 against 1-45 carry-on column input, double digit answer window to centre, groups of five number markers to outer frame, in polished brass mounted on oak base, with operating scribe; an original Webb Adder machine advertising leaflet, with testimonies of users and companies; and an original Webb Directions and Explanations sheet - (3) 6.3/4in. (17cm) wide
