There are mines of offensive and defensive purposes—such as you lay in front of your own harbors to protect you, and such as you lay in front of the doors of your enemy. The first ones you might want to move again; therefore, they are so constructed that you can handle them again, provided you know the secret of construction. The other kind you don’t expect to touch again, and they are, therefore, so constructed that anyone who tampers with them will blow himself up. Secondly, should the Italians surprize us, there would be little chance for us to escape. We could steam only about ten knots an hour, while any cruiser or torpedo could steam over twenty. The only armament we had was one 75-millimeter Hotchkiss gun in the bow. There would be no surrender, either. He would blow the barge and his own steamer up first. “Here,” he said, pointing to a tin can the size of a tomato can, with ready short fuse attached, “is the bomb to be thrown in the barge, and here,” looking down into the forward hold, “is the other one, ready to blow us into eternity. Now, if you want to stay, you’re welcome; if not, take the launch back to Trieste.” Capt. M——, after a brief inspection, went back with the launch to Trieste, while I stayed and photographed with the moving picture camera. There is a long international law governing the laying and exploding of mines, and there has been considerable controversy about the unlawful laying of anchored and drifting mines. There are land-, river-, and sea-mines. Mines laid for the protection of harbors are usually exploded by electric batteries from an observing officer on shore. Others are exploded by contact. The mechanical devices to accomplish this are manifold. The policy adhered to is usually to construct a mine so as to incur the least danger, when handling them, to yourself, and with the opposite results to your enemy. This holds true as long as the secret of construction can be kept from the enemy. The Italians on a night invasion had dropped mines on the Austrian coast that would explode when tilted only at an angle of twenty-five degrees. A little vial of acid would spill over and explode the charge. One day, when a heavy sea was running, some of the mines exploded, betraying the location of the mine field, and the Austrians “killed” the rest of them with minesweepers. Mine fields are discovered by shallow-draft steamers looking for them in clear water or dragging for them. The aeroplane is also an excellent scout. From a height of 1,000 feet he can look a good depth into the sea and see a mine or submarine. On my flight over Grado, on the Italian coast, I could see a mine field and all shallows of a channel wonderfully well from a height of 6,000 feet. When the hydroplane sees a mine an automatic float is dropped that marks the locality, and the mines boat comes along and either lifts it or blows it up.