make a trial trip inside of a month," remarked the aged
inventor. "Look here, Mr. Sharp, I made a change in the
steering gear, which I'd like you and Tom to consider."

The three walked around to the rear of the odd-looking
structure, if an object shaped like a cigar can be said to
have a front and rear, and the inventor, his son, and the
aeronaut were soon deep in a discussion of the
technicalities connected with under-water navigation.

A little later they went into the house, in response to a
summons from the supper bell, vigorously rung by Mrs.
Baggert. She was not fond of waiting with meals, and even
the most serious problem of mechanics was, in her
estimation, as nothing compared with having the soup get
cold, or the possibility of not having the meat done to a
turn.

The meal was interspersed with remarks about the recent
airship flight of Tom and Mr. Sharp, and discussions about
the new submarine. This talk went on even after the table
was cleared off and the three had adjourned to the sitting-
room. There Mr. Swift brought out pencil and paper, and soon
he and Mr. Sharp were engrossed in calculating the pressure
per square inch of sea water at a depth of three miles.

"Do you intend to go as deep as that?" asked Tom, looking
up from a paper he was reading.

"Possibly," replied his father; and his son resumed his