178 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1907. 
mitter produces undamped continuous oscillations these can be re- 
duced to such small amplitude that they will not affect other neigh- 
boring wireless nonsyntonic receivers even if only a little out of tune, 
but can by the cumulative effects of resonance actuate their own cor- 
responding or exactly syntonized receiver at the same or a greater 
distance. This claim is based on the known fact that for certain 
types of receiving circuit, the current created in them can be largely 
increased by increasing the number of oscillations in the incident 
train of waves, so that if oscillations or waves are undamped they can 
make up for feebleness by their persistency. ‘This, however, depends 
essentially upon the nature of the receiving circuit, and is only true 
within certain limits. 
When electric waves radiated from one antenna fall on another 
syntonized or tuned secondary circuit they set up oscillations in the 
latter of the same period. It might be thought that if these imping- 
ing waves are undamped, we should have an infinitely large current 
produced in the secondary circuit. As a matter of fact we do not. 
The electro-motive impulses from the sender only increase the second- 
ary current up to a certain point. The secondary circuit necessarily 
possesses resistance and other sources of energy dissipation which 
rapidly increase with the current induced in it. Moreover, when the 
secondary circuit has an antenna attached, this itself radiates part 
of the energy it absorbs. Hence it follows that beyond a certain 
point the energy thrown onto the secondary circuit is no longer 
utilized to increase the current in it, but only just suffices to maintain 
it. The case is exactly analogous to that of a body being warmed by 
radiant heat. A thermometer exposed to full sunshine only rises to a 
certain height. 
A comparison between the damped and undamped radiation, to be 
valid, must be made as follows: Assume that we have two wireless 
transmitting stations side by side, one sending out intermittent trains 
of feebly damped oscillations, the other continuous trains of un- 
damped oscillations, and let them be so adjusted that the transmitters 
take the same mean power to work them. Let the frequency of these 
damped and undamped waves so radiated be the same. At a dis- 
tance let there be a suitable movable receiving station, say a ship, 
with receiver tuned to the same frequency. Then the principal 
question at issue is, whether the undamped waves can affect this re- 
ceiver at a greater distance than the damped waves of the same in- 
tegral energy. Otherwise, at the same distance can the undamped 
wave station affect the receiver when using less power than the 
damped wave station. Since, however, by assumption the undamped 
waves from one station have the same integral energy as the damped 
waves from the other, the latter will have a higher initial value in 
each train to compensate for their decreased value and intermittent 
