298 Mr. 11. II. M. Bosanquefc on the Present 



enclosed in ordinary brass instruments, is of high practical 

 importance. This study has lately for the first time been 

 put on a sound footing by Mr. Blaikley (I. c). The exami- 

 nation of different forms opens up a considerable field of work. 



Changes of Temperature. 



The effect of changes of temperature on sounding columns 

 of air, tuning-forks, and other sounding bodies, still requires 

 investigation. It remains unexplained, for instance, why 

 small organ-pipes are more affected by changes of temperature 

 than large ones. The accurate laws of the change remain also 

 to be ascertained. 



Velocity of Sound in Tubes. 



The laws of the variation of the velocity of musical sounds 

 of different pitch, in tubes of varying diameter, have been for- 

 mulated*; but the results obtained by different investigators 

 do not agree, and this important element is consequently un- 

 certain to quite a considerable extent. There appears to be 

 no reason why this should not be cleared up by the use of 

 proper appliances. 



Quality of Organ-pipes. 



The mechanical conditions under which sound of different 

 qualities is produced are not understood in all cases. We 

 know empirically that an organ-pipe of large diameter gives 

 a pure tone. In fact the largest-scaled open organ-pipes have 

 their fundamentals so predominant that analysis by beats fails 

 to detect any harmonics. For investigations as to the lowest 

 limit of audible sounds there is, therefore, no apparatus to be 

 compared with a large-scale 32-foot open diapason as it stands 

 on the organ. The notion that stopped pipes are preferable is a 

 mistake. Whether it be that stopped pipes are not made of suf- 

 ficiently large scale I do not know; but it is generally easy to 

 demonstrate, by a simple process of analysis by beats, that 

 stopped pipes drop their fundamental about the middle of the 

 32-foot octave, or at about 25 vibrations per second, whereas 

 with open 32 's the fundamental remains approximately un- 

 mixed to the very lowest pair of notes. As we diminish the 

 depth of the pipe from back to front, the predominance of the 

 fundamental diminishes ; and as we continue, we come to a 

 point where the pipe cannot be made to speak its fundamental 

 at all. Further investigation is required. 



* See Pogg. Ann. new series, ii. p. 235; also Pogg. Ann. cxxxiv. 

 p. 177. 



