sle Another point in connection with the use West, also secure from rear attack. Be- of buoyant mines is the necessity of con- tween these two islands flows a deep- structing them in such manner that they be rendered impervious to the constant water main channel, which is divided into East and West… … Fig. 3 feet, and flows at the rate of from 2 to 4 knots per hour. The nature of the bot- tom is mud. ceive from the passage of friendly vessels In planning the submarine defense of if planted at the entrance of an impor- any harbor the points to be taken into tant harbor ; and the chances of acci-…
Engineering
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