"We'll put her into the water to-morrow," announced the inventor after supper one night. "Everything is complete as far as I can make it, and the only thing remaining is to see if she will float, sink when I want her to, and, what is most important, rise to the surface again. For," he added with a twinkle in his eye, "anybody can make a ship that will sink, but it isn't every one who can make one that will come to the surface again." "Golly! I hope dis chile ain't goin' to git in no subicecream ship what'll stay down under de water so de fishes gits him!" exclaimed Washington, opening his eyes wide. "Dat's worser dan freezin!" "Can't you swim?" asked Mark with a wink at Jack. "Co'se I can swim, boy. I can swim like a starfish, but I can't wif ten thousand tons of a subicecream ship on my back." "A sub-ice-cream ship is a new one," commented the professor with a smile. "It's a submarine, Washington." "I can't see no difference," persisted the colored man. "Subicecream am good enough for me." That night Mark and Jack were thinking so much of the proposed test of the ship the next day that they each dreamed they were sailing beneath the waves, and Jack woke Mark up by grabbing him about the neck during a particularly vivid part of the vision. "What's the matter?" inquired Mark, sleepily. "I thought the ship turned over and spilled me out and I was drowning," explained Jack. "I grabbed the first thing I got hold of and it happened to be you." "Well, as long as you're safe you can go to sleep again," said Mark. "I dreamed I was chasing a whale with the _Porpoise_." The boys were up early the next morning, and found the professor and Washington before them. The inventor was inspecting the track which had been built from the shed down to the water's edge to enable the _Porpoise_ to slide into the ocean. With him were the two machinists, Henry Watson and James Penson. They had been busy since daylight making the ways secure. "She goes in after breakfast," announced the professor, "and I'm going to let you christen her, Washington." "Me? I neber christened a ship," objected the colored man. "Nothing like learning," remarked Mr. Henderson. "Has you got the bottle ob wine?" asked Washington. "I guess soda water will do," said the inventor. "Now look sharp, boys. Get your breakfasts and we'll see if the ship will come up to our expectations." No one lingered over the meal. When it was finished the professor gave Washington a few instructions about breaking the bottle over the nose of the _Porpoise_ as she slid down to the water, for there was no bow to such a queerly shaped vessel as the submarine. At last all was in readiness. The two machinists knocked away the last of the retaining blocks and eased the ship slightly down the well-greased timbers of the ways. "There she goes!" cried the professor. "Break the bottle, Washington!"