Now when a U-boat, or any other kind of a power vessel, gets within a certain range of the chaser the hum of the machinery in her sets the hull into vibration and you can hear it in the receivers. So, you see, whether a U-boat is afloat or submerged it is pretty hard for her to escape the eternal vigilance of the chaser. We had received word by wireless that a U-boat had been sighted about a hundred miles off the coast and that she was one of gigantic size. We swept our area with great zeal, the lookouts in the crow’s nest being changed every two hours; the gunners were at their guns ready for instant action and John Paul Jones Boggs, the other operator and I took turn about listening-in. I don’t want to brag about myself but I found out a long time ago when I was a kid operator back home that I had a more sensitive ear than any of the other fellows, that is, I could differentiate dots and dashes and take down messages that they could only get as a jumble of signals. Later on I began to experiment with head-phones and tried out every make I could get hold of in order to find one that was particularly sensitive and especially suited to my ear. When I was chief wireless operator on the _Andalusian_ I met operators from all over the world. Once when I was in London I scraped up an acquaintance with a young Swede and he had about half-a-dozen pairs of head-phones that he had picked up in different countries. Telephone receivers for wireless work are like violins in that no two of them are alike and you can’t tell by their appearance what they are really worth; like violins, too, telephone receivers improve with age provided the magnets are made of the right kind of steel and properly tempered. One of the pairs of head-phones this Swede operator showed me was made in Sweden by the _Ericsson Telephone Manufacturing Company_, and it was by far the most sensitive phone I had ever used. I bought the pair off him for a _sovereign_ but they are worth their weight in gold. With this pair of Ericsson’s on my head I was listening-in for all I was worth. I kept this up intermittently for about 6 hours when I was rewarded by hearing the faint whirring sound of a propeller. I reported it to my commander and he said it was a U-boat all right. He had our engine stopped so that I could hear her to the best advantage. The sound of her machinery through the water got a little louder and then stopped entirely and we guessed that she was resting. Not to be fooled we stuck right to our posts another five hours but there was nary a sound from her. Then the lookout in the crow’s-nest telephoned down that he had sighted the periscope of a U-boat. Did you ever see a field of race horses just before the signal was given them to start? Well, every man-jack of us felt just as high strung and spirited only we didn’t show it. The commander ordered me to signal all the other U-boat chasers of our squadron to join us.