There were many different anti submarine devices. There were nets underwater, along with mines. Torpedoes are the current main weapon. There were also depth charges and the hedgehog used by ships to create explosions under the water.
Underwater objects are usually tracked by means of the sounds given off by an object. For a submarine, sound is generated largely by its propellers as they churn through the water. However, the engines and some other parts also generate noise. These noises are detected by a submarine's sonar (sound detection and ranging equipment).Objects can also be located by reflected sound waves, known as "active sonar". A "ping" or sound wave is generated into the water. Any differences in the returning sound indicates the location of an object or structure underwater. This technique can also be used to map the ocean floor.
The submarine telescope was not invented by an individual but rather refers to a scientific concept of placing a telescope in an underwater observatory to observe celestial objects. This concept is still being developed and researched by scientists and engineers.
Sonar
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Credit for the invention of the submarine is sometimes given to William Bourne, a British mathematician and ex-Royal Navy gunner, who published a design in 1578.
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Answers.com blocks the use of url's in answers given, so we can't help you. But google 'unrestricted submarine warfare WW 1" and those sites will appear.
This is known as an oceanic trench.
All Submariners, regardless of rank, are always in some type of training, either underway or in port. There is no "training dive" if that's what you're referring to. All new crew members submerge with everyone else. I was asleep for my first submergence. Submarine Sailors are trained at Submarine School in Groton on basic submarine operation, damage control techniques, history, and many other subjects pertaining to submarines as a weapons platform. No one who is assigned to any submarine is ever clueless - even in Submarine School you are tested to see if you can properly deal with pressure changes in a controlled pressure chamber. You are placed in a Damage Control trainer (known as the "Wet Trainer"), in which you're subjected to real-world flooding and damage conditions and expected to deal with them. You are given training on a Control Room simulator as well. In other words, you're not thrown in blind. Everyone knows what to expect before they get there.
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Vergin is a type of plane.