The Boehm system of fingering, which was introduced about 1846, consists in making the keys (which formerly closed by springs) open automatically, the closing being effected by means of rings round the finger holes. By adopting this device, holes can be bored in more correct positions, and the Angers are not strained by stretching. Bass fingered wood-wind instruments are also made possible. Even in the flute the holes are very far from being in their best position. In the accompanying illustration of a flute it will be seen that the lowest finger hole is too high; if it were in its right place it would be too far for the third finger to close it, therefore it is brought nearer, and made smaller, the result being that what is gained in convenience is lost in tone. Siccama therefore made his fiutes with open keys for this and the corresponding hole on the middle joint, closing them by leverage, which is brought to an easy position for both of the third fingers. Another advantage of the Boehm system is the better manipulation of the fingerings, by which the alternate opening and closing of the holes work the keys which produce the chromatic sounds.

In the one-keyed flute, nearly all these sounds must be produced in this way; and even when keys are provided it is sometimes easier to use the fork or cross fingerings. Thus, let 1, 2, 3 represent the right-hand fingers, and all closed holes represent D, 1 and 2 closed E, 1 closed F sharp; the fork for F natural would be 1, 3 closed, 2 open. Now if hole 2 is bored, so that with hole 3 open it makes a good F sharp, it by no means follows that the closing of 3 will enable the open hole 2 to produce a true F natural. By the use of a small auxiliary hole, and rings round 2 and 3, both sounds can be made perfect. If the Eoehm system could have been adopted in its entirety, self-closing keys would have been superseded by self-opening keys; but that being found impracticable, the system has been modified, and is partially applied to very many instruments, one of the most advantageous being Barre's improvements for oboes and clarionets. It is really a combination of old and new systems, whereby a lever allows the self-opening keys to act, while they are closed by rings round the proper holes when they must be shut.

System of Fingering Flute.