288 Proceedings of Indiana Academy of Science. 
varying the connections to the coil, L, and by changing the capacity at C. 
Two tubes or two sets of tubes are used. 1, is one or more power tubes or 
hard tubes connected in parallel. Two power tubes are shown in the figure. 
These tubes are the oscillating tubes by means of which the energy is sent 
out into the aerial. 2, is an ordinary receiving or amplifying tube by means 
of which the current from the telephone transmitter, T, is amplified. The 
transmitter, T, is connected in series with a resistance, R, and a battery, D, 
of two or more ordinary dry cells. The resistance R, should have a resist- 
ance equal to that of the transmitter, T. The variation of the current 
through the carbon transmitter causes a variation of the potential 
difference at the terminals of the resistance, R, This varies the poten- 
tial of the grid of tube, 2, and causes a coresponding variation of the current 
of the plate circuit of tube, 2. This current flows through the grid leak 
resistance, R. and thus modulates the amplitude of the current sent into 
the aerial by the tubes, 1. R. should be a resistance comparable to the im- 
pedance of tube 2. The battery B is an ordinary plate battery of 20 or 40 
volts. H is a source of high potential, about 300 volts. 
This circuit has been tried out using an aerial of poor construction. The 
results compare yery favorable with some of the standard connections. With 
an antennae current of 200 milliampers the voice was transmitted to a coil 
aerial of six turns 2 meters square at a distance of one-half mile. This 
should lead one to expect the range should be five or ten miles with a good 
receiving aerial. 
The resistance, R,, was an ordinary resistance box. R., was made of card 
board painted with india ink. 
