MUSICAL INSTRUMENTS — RICHARDSON 259 



of the hole size and position on the woodwind, in place of the old 

 hit-or-miss method, is our uncertainty in ascribing precise values to 

 these admittances, or end corrections. Work is, however, proceeding 

 on this problem. 



The material of the tube seems not to have such a marked effect on 

 the output as some organ builders suppose. Provided the tube is not 

 made of very lissom material it will sound — even shellacked paper will 

 serve — though there may be differences in harmonic development. In 

 plate 1, figure 2, are shown tracings of the wave form of four metal 

 diapasons (C 520) of different material but identical shape. It will be 

 noticed that there is some change in the strength of the second and 

 third harmonics. 



The nature of the coupling between exciter and resonator is a 

 matter that has interested workers in musical acoustics of late. In 

 a flue pipe the edge tone, which, unmodulated, would normally have 

 a pitch proportional to the wind velocity, is brought into consonance 

 with one of the natural modes of vibration of the column — the funda- 

 mental at moderate pressure, the overtones at higher (overblown) 

 pressures. Exceptionally, if the pipe is underblown, a reshuffling of 

 the pendulations in the jet takes place whereby either the fundamental 

 or its octave again appear. Although these underblown tones are 

 undesirable they often appear transiently as the blowing starts. Thus 

 in the oscillograph record of the commencement of sounding of the 

 diapason pipe, reproduced in plate 2, figure 2, «, the octave is apparent 

 in the transient for about one-tenth of a second though not in the final 

 wave form. The buildup of pressure in this pipe lasted about one-fifth 

 of a second. Transients also occur on wind instruments when the 

 player passes portamento from one note to another (pi. 2, fig. 2, c) . 

 The process of "voicing" by which an organ builder gets the pipe 

 to speak as he wants it, cutting the mouth and making notches in 

 the lower lip, is a mysterious art which I hope will be clarified in 

 a scientific study of the process being made by Mr. Mercer at the 

 University of Southampton. 



In a reed pipe the coupling between reed and column may be either 

 tight or loose. If the reed is slim and rather inelastic because of its 

 moist condition — like many orchestral reeds, including the brass- 

 player's lips — it accommodates itself to whatever note the player 

 and/or the wind pressure imposes on the column. In the organ reed 

 pipe, however, the reed is strong and elastic, and if reed and column 

 are tightly coupled the two can only sound sympathetically when the 

 length of the pipe is adjusted to synchronism with the reed ; otherwise 

 the system remains silent. 



With the partners loosely coupled, the main function of the reso- 

 nator is to purify the rather raucous sound of the reed by smothering 



