I can personally testify to the difficulty of identifying a mystery ship. One day Admiral Bayly suggested that we should go out in the harbour and visit one of these vessels lying there preparatory to sailing on a cruise. Several merchantmen were at anchor in port. We steamed close around one in the Admiral's barge and examined her very carefully through our glasses from a short distance. Concluding that this was not the vessel we were seeking, we went to another merchantman. This did not show any signs of being a mystery ship; we therefore hailed the skipper, who told us the one which we had first visited was the mystery ship. We went back, boarded her, and began examining her appliances. The crew was dressed in the ordinary sloppy clothes of a merchantman's deck-hands; the officers wore the usual merchant ship uniform, and everything was as unmilitary as a merchant ship usually is. The vessel had quite a long deckhouse built of light steel. The captain told us that two guns were concealed in this structure; he suggested that we should walk all around it and see if we could point out from a close inspection the location of the guns. We searched carefully, but were utterly unable to discover where the guns were. The captain then sent the crew to quarters and told us to stand clear. At the word of command one of the plates of the perpendicular side of the deckhouse slid out of the way as quickly as a flash. The rail at the ship's side in front of the gun fell down and a boat davit swung out of the way. At the same time the gun crew swung the gun out and fired a primer to indicate how quickly they could have fired a real shot. The captain also showed us a boat upside down on the deckhouse--merchantmen frequently carry one boat in this position. At a word a lever was pulled down below and the boat reared up in the air and revealed underneath a gun and its crew. On the poop was a large crate about 6 x 6 x 8 or 10 feet. At a touch of the lever the sides of this crate fell down and revealed another gun. III