22 



ILLINOIS STATE ACADEMY OF SCIENCE 



2. The tube under normal conditions emits a pure 

 tone which is the fundamental, as shown by photographs 

 of the wave form. 



3. The vibrating air column is accurately one quarter 

 of the wave-length of the tone emitted. 



4. The pitch may be varied over a wide range by 

 extending or shortening the length of the vibrating air 

 column. 



5. The air within the tube is set in violent stationary 

 vibration. 



6. Because of the purity of the tones emitted two 

 singing tubes sounded simultaneously are well adapted 

 for the production and study of beats. 



7. This vibration results in there being a consider- 

 able back pressure at the inner end of the vibrating col- 

 umn. 



8. If the tube is lengthened indefinitely the funda- 

 mental dies out and overtones appear instead. At times 

 the two may be heard simultaneously. 



9. The intensity of the tone emitted may be increased 

 many fold by attaching a horn. 



10. Each tube has a particular point at which the heat 

 must be applied in order that maximum intensity of 

 sound may be attained. 



11. The pitch is practically unaffected by changes in 

 the heating temperature, while the intensity is very much 

 increased with increase of heat. 



12. The tube may be used as a standard of sound to 

 the extent that the energy (heat) supplied can be kept 



t 



•III - 



u 



eoii 



V 



U 



i t 3 ^ 



pn 



kot 



hot 



8 



\ / \ Y 



to 



Figures 1-10 



A Physical Explanation of the Action of the New Singing Tube. 

 By Chas. T. Knipp and Jacob Kunz, November, 1921. 



