PAPERS PRESENTED AT GENERAL SESSIONS 21 



''PRODUCTIOX OF SOrXD BY THE APPLICA- 

 TIOX OF HEAT" 



(Experimental) 



Chas. T. Kxipp, ITxiveesity of Ildixois 



(Abstract of Eetiring President's Address) 



That a tone of considerable intensity may be produced 

 by heat is not new. Lord Eayleigh in his treatise on 

 *' Sound" describes several experiments dating back as 

 far as 1875, in one of which a sonorous sound was ob- 

 tained by placing a small flame within and near one end 

 of a glass tube. This experiment, which is referred to in 

 all text books on physics, is kno^^^l as Rijke's experiment 

 and was possibly the best example of the production of 

 sound by the application of heat until recently. Another 

 example is the glass blower's bulb in which a freshly 

 bloA\Ti small glass bulb while still hot emits a clear tone 

 as the stem is removed from the lips. Both of these in- 

 stances are fully discussed by Eayleigh, yet the true ex- 

 planation of the cause of the tone, especially in the latter 

 case, is not clearly understood. 



Several years ago the writer chanced to be working 

 with Pyrex glass (the new refractory glass from which 

 baking dishes are made) and while blowing a tube to 

 serve as a mercury vapor trap, it, quite by accident, be- 

 gan to emit a clear and apparently pure tone. The emis- 

 sion of the note was unlooked for and came as a complete 

 surprise. The phenomenon was as unusual as it was 

 novel and it at once suggested a fruitful field for research. 

 It proved to be intensely interesting and many striking 

 and unusual phenomena were recorded. 



TThile the ''singing tube", as it came to be kno-v\Ti, 

 seems to be primarily of scientific and educational value, 

 yet there is also a practical aspect. The following ex- 

 periments and observations have been made : 



1. The tube may have a variety of forms; however, 

 the underhdng principle of sound production is the same 

 in all. 



