290 ProcrrdiHys of fndiana Academy of Science. 



The tnning of the primary coil is liy means of a variable condenser in series 

 or in multiple witli all or a ]»ortion of the primai'y coil. 



The inductance of the coils as wound is secondary, .0185 henry ; and pri- 

 mary, .0228 henry. The total resistances are, 8.1 ohms and 9 ohms re- 

 spectively. The natural wave length of the entire secondary coil as meas- 

 ured with a wave meter is 11(M> meters, which corresix)nds to a distributed 

 capacity pf .000019 microfarads. The dead end switches break this so that 

 the energy ab.sorbed is a minimum. 



As mounted as a slide tuner the length over all is 22 inches. The total 

 weiglit is 15 pounds. An equivalent long wave receiver coil of the single 

 layer type would require five times as much wire and would be 25 times 

 as long or a length of about 45 feet. 



Thus we liave in small dimensions a receiver for any wave length from 

 Ainiapolis 17000 meters to amateur stations 200 meters. European sta- 

 tions are received with one liulb using an aerial 125 feet long stretched 

 among the trees of the Indiana University campus. 



