d by being under water.
But we'll soon get used to it. Luckily, the _Porpoise_ was not damaged
by the shock."

For several hours the _Porpoise_ was kept on her course. She behaved
handsomely, and nothing excepting slight and easily remedied defects
were found. The professor steered well out to sea, increasing both the
forward speed and the depth to which the vessel sank. Presently the
craft came to a stop with a little jolt.

"What's the trouble?" asked Mark, somewhat alarmed.

"Nothing at all," replied the professor with a smile, as he stepped out
of the conning tower and entered the engine-room. "I thought it was time
for dinner so I stopped the ship. We are now resting on the ocean bed,
about half a mile below the surface. Look!"

As he spoke he slid back the slides covering the plate glass windows.
The boys saw that the ship rested in the midst of an immense forest of
sea weed. Some of the stalks were as large around as trees. In and out
among the snake-like, waving branches swam big fishes. It was a weird,
but beautiful sight.

"Come, Washington, serve dinner," ordered Mr. Henderson, and the colored
man soon had a good meal prepared. Few repasts have been eaten under
such strange circumstances.

Desiring to be back at his secluded dock by nightfall, Captain Henderson
soon started the _Porpoise_ up again. Without any accidents the return
trip was made and by nine o'clock the _Porpoise_ rode safely at the
dock where she had been launched.

The night was spent in the cabin on shore. Early the next morning Mr.
Henderson paid a visit to the ship, to make a thorough examination by
daylight, and see if the craft had suffered any damage.

"I think you and Mark will have to make a trip to town," he said to Jack
at the breakfast table. "I need a new monkey wrench and some other tools
and some small pieces of machinery. I'll give you a list of them, and
you can bring them back in a valise, for they will be quite numerous."

After the meal the inventor made a record of what he needed and the boys
started off.

"In case the machine shop does not have everything and you have to wait
for something, you had better stay in the town all night," the captain
of the _Porpoise_ said. "It is quite a long trip and I don't want you
traveling after dark. Put up at the hotel if you are delayed."

Provided with money for their purchase, and a large valise in which to
carry them, the boys started off. They had to walk two miles to