It was connected with the river several hundred yards below by means of a canal and a lock.
In the center of the tank floated the submarine boat.
It was a wonderful specimen of seacraft. The two new-comers gazed at it spellbound.
In shape the Dolphin was long and rakish and her lines indicated speed. Her hull was of plates of steel.
Her main deck was roofed over entirely, giving her an odd appearance as she lay there in the water. In this roof was an enormous plate-glass skylight and any number of dead-eyes.
These were wholly for purposes of observation from the interior of the boat. There was a large observation window and conning tower upon each side of the vessel about midships.
A pilot-house with a conical dome and heavy glass windows was forward. There was an outer deck or platform to the width of six feet, which extended all around the vessel and was protected by a guard rail.
The Dolphin had three steel masts and a long bowsprit with rigging of steel ropes. These were more for the steadying of the craft than practical use.
She had twin screws, which were driven by powerful electric engines on a peculiar storage plan, which was wholly the invention of Frank Reade, Jr.
So light and clean cut was the Dolphin that she could make a famous rate of speed even under water.