You will require to add _fresh_ water now and then, in order to keep it at the same degree of saltness as the sea." "Very true, Jack, that never struck me before," said I.
"And, now I think of it," continued Jack, "it seems to me that the surest way of arranging your tank so as to get it to keep pure and in good condition, will be to imitate the ocean in it.

In fact make it a miniature Pacific.

I don't see how you can hope to succeed unless you do that." "Most true," said I, pondering what my companion said.

"But I fear that that will be very difficult." "Not at all," cried Jack, rolling his towel up into a ball, and throwing it into the face of Peterkin, who had been grinning and winking at him during the last five minutes.

"Not at all.