Hank Sterling donned a hydrophone headset and listened intently.
The Adriatic Sea was an ideal place for the use of the hydrophone.
Then came the store rooms and wireless and hydrophone rooms.
Many U-boats were chased to their doom by the aid of the American hydrophone.
The development of the hydrophone for anti-submarine work, both from ships and from shore stations.
A destroyer travelling at full speed on a calm sea, when heard on a hydrophone resembles the roar of a gigantic dynamo.
Nevertheless the hydrophone is a submarine instrument with a brilliant future.
The "water noises" were reduced and, greatest improvement of all, the hydrophone was made "directional."
There were many different types of hydrophone in use during the Great War.
With the perfection of this invention the hydrophone section of the naval service came into being.