186 B. Davis — Small closed Cylinders in Organ-pipes. 



one end, as was described by the writer in this Journal.* The 

 torsion balance carrying this cylinder was placed at the middle 

 of the loop. 



The small cylinders whose spacing in the sound wave was to 

 be measured were of two kinds, consisting of small gelatine 

 capsules and of paper tubes. These two kinds of cylinders 

 were used in independent series of experiments. 



Three sizes of gelatine capsules were used, commercial num- 

 bers of which are Nos. 00, 2 and 5. 



The dimensions in centimeters of these cylinders are given 

 below. 



Length. Diameter. 



No. 00 .__ _. 2-42 -83 



No. 2 1-75 -63 



No. 5 1-03 -48 



A sufficient number of one of the above sizes of capsules 

 were placed in the organ-pipe to form a considerable number 

 of rows. In order to obtain a desirable amplitude of vibra- 

 tion the torsion head was turned from the zero position by an 

 amount corresponding to a desired amplitude, then the pres- 

 sure of blowing was increased until the force acting on the 

 measuring device just balanced the torsion previously given to 

 the wire ; at the same time the capsule cylinders arranged 

 themselves in rows across the pipe. This previous setting of 

 the torsion head enabled me to reproduce the same amplitude 

 of vibration at will. 



In the tables below are given the average distances in centi- 

 meters between the rows for the various sizes, with increasing 

 amplitudes of vibration. The amplitude 2A is here used to 

 denote the total excursion of the vibrating air particles. 



No. 00. Capsule cylinders. 



Amplitudes. Number of rows. 



, » s ( * , 



2A 2 3 6 10 



•39 4- 3-5 2-8 2"2 



•434 3-5 3-3 2'6 2'1 



•476 3'3 3-5 26 2*1 



•548 3-5 3-7 2-7 2*2 



No. 2. Capsule cylinders. 

 Amplitudes. Number of rows. 



2A 2 3 6 10 



•39 2-8 2-75 2-8 2' 



•434 2*4 2*5 2'65 1'95 



•476 2-5 2-5 2-55 2- 



•548 2-5 2-5 2'45 2; 



* This Journal, September, 1900. 



