272 Mr. 0. W. H. Foord on Aiv-Pressures 



Mr. S. 0. Laws, in connexion with brass instruments with 

 cup-shaped mouthpieces, viz. : the trumpet, cornet, and 

 trombone ; a full description of their most interesting ex- 

 periments being reproduced in the ' Proceedings of the 

 Physical Society of London,' vol. xviii., and also in the 

 Philosophical Magazine for April 1902. 



The experiments made by Dr. Barton and Mr. Laws upon 

 the three instruments just referred to, showed that the 

 tendency was for the wind-pressures to rise with a rise in 

 pitch of the notes played, in Dr. Stone's table a similar 

 rise of pressure with rise of pitch is indicated for every 

 instrument which he mentions, except the clarinet, the other 

 instruments being the oboe, bassoon, horn, cornet, trumpet, 

 euphonium, and bombardon. The pressures, according to 

 Dr. Stone, from the lowest notes to the highest notes on the 

 clarinet varied from 15 inches of water to 8 inches, the 

 clarinet thus displaying a remarkable peculiarity. 



Dr. Stone's table of wind-pressures has been reproduced 

 in several works by other writers, and some of these have 

 assumed that the figures given by Dr. Stone for the clarinet 

 were incorrect, two writers to the present author's knowledge 

 having altered the figure 8 to 18 without making any 

 comment, on the assumption, I suppose, that the figure 8 was 

 a misprint. This curious disagreement between the wind- 

 pressures for the clarinet as given by different writers, 

 caused me to make a series of experiments with a view to 

 verifying Dr. Stone/ s figures. These experiments were also 

 extended to the saxophone, which is a brass instrument 

 employing a mouthpiece and single reed similar to those 

 employed on a clarinet, but having a conical bore and 

 hence a scale corresponding with that of t lie oboe. That is 

 to say, it ''overblows''' to the octaves of the fundamental 

 tones, whereas the clarinet, which has a cylindrical bore, 

 ''overblow.-'* to the twelfths. The word '"overblows" is a 

 convenient one in this connexion, but it will be seen from 

 the following experiments that it is not literally correct 

 when used in connexion with the single-reeded clarinet and 

 saxophone. 



The method followed in carrying out the experiments 

 corresponds with that adopted by Dr. Stone and also by 

 Dr. Barton and Mr. Laws. The pressures were taken by a 

 water-manometer, similar to that used by organ-builders ; 

 connected to the mouth when playing by means of an india- 

 rubber tube held in the corner of the mouth. 



