were to have.

The next few days were busy ones. Many little details remained to
perfect in connection with the ship, and a lot of supplies and
provisions had to be purchased, for the professor was determined to get
all in readiness for the trip under the water. He believed firmly that
his ship would work, though some of the others were not so positive.

"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 c