George III's double-barrelled air pump
1761
Surface Condenser and Air Pump, England, 1775
1775
Air pump
1871-1900
Double-barrelled air pump, late 18th century.
1766-1795
Single-barrelled air pump, late 18th century.
1770-1790
Double-barrelled air pump with bell jar by Dollond family
1780-1820