n was in the yard for a few minutes, and I got him
to put me on board. I figured I could hail somebody else when I was ready
to go on shore."

"But what on earth made you do such a thing?" demanded Captain Jack, in a
low tone. "It's really more than you had a right to do, Eph, without
getting Mr. Farnum's permission."

"Why, I've known you to take the 'Pollard' and try something when Mr.
Farnum wasn't about," retorted Somers, looking surprised.

"You never knew me to do it when I could ask permission, although, as
captain, I have the right to handle the boat. But that leave doesn't
extend to all the rest, Eph. What were you doing down there, anyway?"

"Why, I came on board, and left the manhole open for ten minutes,"
answered Somers. "Then I found the cabin thermometer standing at 49
degrees. I wondered how much warmth could be gained by going below the
surface. I had been down an hour and five minutes when you began to signal
with that sledge-hammer--"

"Sounding-lead," Jack corrected him.

"Well, it sounded like a sledge-hammer, anyway," grinned young Somers.
"While I was down below I found that the temperature rose four degrees."

"Part of that was likely due to the warmth of your body, and the heat of
the breath you gave off," hinted Benson.

"You could have gotten it up to eighty or ninety degrees by turning on the
electric heater far enough," suggested Hal.

"I wanted to see whether it would be warmer in the depths; wanted to find
out how low I could go and be able to do without heat in winter," Somers
retorted.

"I could have told you that, from my reading, without any experiment,"
retorted Skipper Jack. "Close your conning tower and go down a little way,
and the temperature would gradually rise a few degrees. That's because of
the absence of wind and draft. But, if you could go down very, very deep
without smashing the boat under the water pressure, you'd find the
temperature falling quite a bit."

"Where did you read all that?" inquired Eph, looking both astonished and
sheepish.

"Here," replied Jack, going to a small wall book-case, taking down a book
and turning several pages before he stopped.

"Just my luck," muttered Eph, disconsolately. "Here I've been dull as
ditch-water for an hour, trying to find out something new, and it's all
stated in a book printed--ten years ago," he finished, after rapidly
consulting the title-page.

Jacob Farnum had been no listener to this conversation. Taking