382 



PROCEEDINGS OF THE AMKKKAN ACADEMY. 



Tided with a conical sound-collector 29 cm. in diameter, was placed at 

 a distance of about l."> meters from the organ-pipe. The In' ohm prim- 

 ary and the 7"_'<» ohm secondary of the transformer, Figure 2, were em- 

 ployed The galvanometer G was a d'Arsonval type and had .i resistance 

 ,.t' :..;s ohms, and gave a throw of one scale division d 1 ,, inch) for a 

 current of 1.53 x Kr 8 amperes. 



The condenser C, Figure 2, having a total capacity of 1 microfarad, 

 and adjustable by steps of .<>"> microfarads, was given various values, 

 and the corresponding throws of the galvanometer when the pipe 

 was sounded were taken. In taking these readings the pipe was left 

 sounding until the coil of the galvanometer had completed its swing. 



The results are recorded in Table I. 



TABLE I. 



Almcstmkst ok Electric Circuit to RESONANCE with 

 Soi M' Fbbqtjbnci . 



The curve of Figure 3 is plotted from the data of Table I. The hori- 

 Eontal dotted line through the figure is the current with the condenser 



shorl circuited. This curve gives an idea of the advantage obtained 

 by the ase of the proper capacity in the primary circuit of Figure 2. 

 The maximum of the. curve shows a value of the current that i» 

 nearly eight times the current obtained when the condenser was 

 short-circuited. 



