h this valve in the floor. And when the water is all out,
we turn off the stream of compressed air, and open this valve, which
allows the compressed air to pass into the habitable portion of the
ship, quickly reducing the air-pressure in this room to what it is in
the other habitable portion of the ship; then we open this door, and
pass into the diving-room."

The professor then threw open the door and, with a profound bow, stood
aside to allow Lady Elphinstone to pass through.

The room in which the party presently found themselves was an apartment
about twenty feet square, one side of which was wholly occupied by four
cupboards labelled respectively "Sir Reginald Elphinstone", "Colonel
Lethbridge", "Captain Mildmay," and "Von Schalckenberg."

"This," explained the professor, "is the room wherein we shall equip
ourselves for our submarine rambles; and," throwing open the door of one
of the cupboards and disclosing certain articles neatly arranged upon
hooks fastened to the walls, "here is a suit of the clothing and armour
that we shall wear upon such occasions."

"Oh yes," responded Lady Olivia, "I remember having heard Sir Reginald
speak of his `diving-armour'; what a very handsome suit it is,"--as she
touched and thoughtfully opened the folds of a surcoat of scale armour
that looked as though made of silver; "but it seems a queer idea to don
armour for the purpose of walking about at the bottom of the sea. Yet,
what a man of foresight you must be, Professor! My husband has often
told Ida the story of your terrible fight with the conger eels, the
first time that the party ever sallied forth from the _Flying Fish_.
You appear to have foreseen and provided against every possible danger."

"No, no!" exclaimed von Schalckenberg, laughingly disclaiming any such
prescience; "I am not nearly as clever as that. For instance: the
armour was not provided as a protection against the attacks of savage
animals or fish, but for quite a different purpose."

"Indeed!" exclaimed her ladyship; "for what purpose, then, was it
provided?"

"For the purpose of protecting the wearer against the enormous pressure
of the water to which he would be subjected when moving about on the bed
of the ocean at a great depth below the surface," answered the
professor. "You must understand," he continued, "that water exerts a
pressure upon everything immersed in it; and the deeper the water, the
greater is the pressure upon the immersed body