It seems that the Russians feared the Japanese might by hook or crook, during the night or at a time of fog, which at that time of the year occurred frequently, get hold of some vessel, equip her with torpedoes, and make a raid on the fleet at anchor. Consequently they had mined all except the principal channel, which could be watched. We immediately stopped the _Protector_, blew tanks, and proceeded with caution back to the main channel and returned to Cronstadt. I felt that we had had sufficient manoeuvres for that day at least. Another experience which came very close to a tragedy was brought about by the spirit of mischief of one of the trial officers while conducting the official trials of the _Protector_ in the Gulf of Finland. One of the trial conditions set by the Russian Government was that we were to be able to run the _Protector_ under her engine with her decks submerged and conning tower awash, I standing in the open hatchway with the _Protector_ running under these conditions, ready for instant submergence, her conning tower being held above the surface by setting her hydroplanes up. By pulling the hatch cover down and inclining the hydroplanes downward the vessel could be almost instantly submerged--submergence not occupying over fifteen seconds. I had so much confidence in the safety of the _Protector_ running in this condition that I did not hesitate to leave the depth-control mechanism for considerable periods of time. During this official trial in the Gulf of Finland we ran through a school of small fish, and, leaving the hydroplane control gear, I went out upon the deck of the conning tower and watched the fish, which could be plainly seen as the _Protector_ passed through them. At this time there was about three feet of water over the decks, and the deck of the conning tower was about a foot or eighteen inches out of the water. All at once the _Protector_ started to go down. I jumped down inside the conning tower, pulling the hatch after me, and I am free to confess that my hair stood on end. I then observed that the _Protector_ had gone back to her normal condition, and saw at the same time that the senior Russian officer, a very tall man who had to stand in a stooping position in the conning tower, was shaking with laughter. Captain Gadd then explained to me that the other officer--I shall not mention his name, because he is now a high admiral--had "set" the hydroplanes a little down for the purpose of seeing if he could frighten me. He frightened me all right, and I assure you that I never ran the _Protector_ afterward in that condition, because I came to the conclusion that, while it might be possible to make a submarine fool-proof, one could never make reasonable calculations which would eliminate danger from the actions of the practical joker. It was only a few weeks after this incident that I read the account of the A-8, one of the diving type of boats in the British Navy, making the fatal