ELECTRIC WAVE TELEGRAPH Y—FLEMING. 179 
cessation. Hence we may ask another question, viz, What will be 
their relative effect on receiving stations in their neighborhood not 
quite in tune with the emitted waves? Can we bring the undamped 
waves nearer into tune with these outlander stations without disturb- 
ing the latter, than we can in the case of the damped waves, and if 
so within what ratio of wave length? Claims have been made for a 
great superiority in this respect in the case of undamped waves, but 
we are still awaiting quantitative confirmation. Among other as- 
sertions it has been stated that the undamped waves are less easily 
“ tapped,” to use the newspaper expression. This isa fallacy. With 
the proper experimental appliances a receiving circuit can be grad- 
ually adjusted to any electrical frequency, and when it comes to the 
right frequency it must be affected just as much as true receiving 
stations for which the waves are intended. It is all a matter of ap- 
paratus and skill. To illustrate the first point, viz, the effect of the 
nature of the receiving circuit we may take an instance from optics. 
When we look through a telescope at the stars we can see a certain 
number down to some limiting magnitude. No amount of prolonged 
gazing when using the eye as a wave receiver increases the effect pro- 
duced by a just invisible star. If, however, we use a photographic 
plate the effect on it is cumulative, and we can by a sufficiently long 
exposure obtain impressions of invisible stars in countless numbers. 
The photographic film is a wave detector of quite a different kind to 
the retina. In the case of the film it can make up by time what is 
wanting in intensity in the wave motion. In the case of wireless 
telegraphy it is clear, therefore, that the nature of the receiver has 
a great deal to do with the possible advantages of undamped waves, 
and it is not merely a question of the tuning or the transmitter.¢ 
Again, the ordinary 10-inch induction coil and spark transmitter as 
used on ships takes up one-fifth of a horsepower when in full work, 
and can send wireless messages 200 miles or more when an appropriate 
receiver is used. I find it very difficult if not impossible to obtain 
“Jn order that he may take the utmost advantage of the principle of res- 
onance, Mr. Poulsen uses in the receiver a device he calls a “ticker.” This 
serves to keep the condenser-inductance circuit of the receiver closed, until 
resonance has exalted the oscillations to the utmost. The ticker then opens 
it at intervals and inserts the particular oscillation detector, whether electro- 
lytic or other, which makes the audible or visible signal. In his syntonic 
receiver Mr. Marconi has always adopted a similar plan, for he keeps the 
coherer terminals joined by a condenser which closes the secondary circuit of 
the receiving jigger. A point of interest not yet considered is whether we do 
need absolutely undamped waves to gain all the possible practical advantages 
derivable from them. It may be that very slightly damped trains containing, 
say, 50 oscillations per train and following each other several hundred times 
per second will with an appropriate receiver give us all that we can obtain 
from the use of forced undamped waves. 
