Barker lever

The Barker lever is a pneumatic system which multiplies the force of a finger on the key of a tracker pipe organ.

This lever allowed for the development of larger, more powerful organs still responsive to the human hand.

The first Barker lever was built in the Cavaillé-Coll organ of the Basilica of Saint-Denis.

This "contrivance" was named after Charles Spackman Barker (1804-79), engineer and organ-builder.

A similar lever was developed by David Hamilton in 1835, and there has been debate whether Barker stole the design.