38
Wireless Telegraphy
near one another, as in the case of two or more boats passing a shore station, the operator may not be able to tune out the undesired party, owing to their proximity, and the apparatus is then said to be operated by “forced oscillations.” Nevertheless an operator may receive the desired message by concentrating his mind upon the sound of the “spark” of the desired transmitting station, but this may only be done when the sounds of the “sparks” are dissimilar, or one is louder than another, owing to different strengths, or to varying distances.
