Compensating valves

System of constructing brasswind instruments whereby the air passage for valve combinations including the operation of a master valve is led through the other of the valve pistons or rotors twice. These latter valves are equipped with two sets of valve loops and tuning slides. The shorter secondary loops add the extra tube length required for good intonation when valves are used in combination This is the principle of the Gautrot's 1858 patent Syst?me ?quitonique, D.J. Blaikley's 1878 patent Compensating Pistons, and some models of Double horn.