William Henry Stone

“ Thus, in an instrument in the key of C, the first valve lowers the pitch to B♭, the third valve lowers it to A♭. For the low G the first valve is used in combination with the third, but its tubing is tuned to give the interval from C to B♭, and as the instrument when the third valve is down is virtually in A♮, the tubing of the first valve is not sufficiently long to flatten the pitch a true tone from A to G. This defect is intensified when all three valves are used together to produce D♭ and G♭. ”

“ The Rotatory valve is simply a 'fourway stopcock turning in a cylindrical case in the plane of the instrument, two of its four ways forming part of the main channel, the other two, on its rotating through a quadrant of the circle, admitting the air to the bypath.' This gives great freedom of execution, but is far more expensive and liable to derangement than the Piston valve. ”

“ In the French Horn, indeed, from the closeness of the harmonics to one another in the part of its scale chiefly used, two valves are sufficient, depressing the note a semitone and a tone respectively. ”