Triptych: Helpful Aids to the Understanding
Instructions for using Dr Abacus's Wunderhut, oiled carbon print
Carte Tendresse, Oiled carbon print
Instructions for using "The Abacus Traveller's Companion."
The Abacus Harmony Tandem Stirrup Pumps. Cast iron columns, brass, blackwood and rubber hose, air.
The Abacus "Harmony" Tandem