302 



ILLINOIS STATE ACADEMY OF SCIENCE 



NOTE ON THE CHARACTERISTICS OF THE NEW 

 SINGING TUBEi 



Prof. Chas. T. Knipp, University of Illinois 



The temperature difference that is necessary to cause the 

 new singing tube to emit a tone, when the portion B (Fig. 

 1) is kept at room temperature while the tip A is heated, 

 was observed to be about 400'' Centigrade. If, however, B 

 is cooled to the temperature of liquid air the temperature 

 difference necessary is greatly reduced, being about 200° 

 Centigrade. The pitch is also considerably lowered. 



f\ i 



B 



C 



figure 1. 

 It was deemed desirable to make quantitative measure- 

 ments of these temperature differences and also of the cor- 

 responding pitch of the tone emitted. To this end B was 

 held successively at different temperatures, ranging from 

 that of liquid air to values considerably above room tempe- 

 rature, while A was heated electrically in each case to a 

 temperature where a tone was emitted continuously. The 

 two portions A and B were each housed within a separate 

 copper tube of about 1 cm. wall thickness and heavily in- 

 sulated with asbestos. The temperatures were accurately 

 measured by means of thermo- junctions — three being at- 

 tached to A and three to B. The temperature control of 

 each section was good and could be held fairly constant 

 at will. 



TABLE I. 



The results from the only run thus far made are con- 

 tained in Table 1. In observation No. 1 the part B was 

 placed within a glass jacket heavily wrapped with asbes- 



1. Phys. Rev., N. S., Vol. XV, p, 336. 



