et Willoughby, which was Mrs.
Strong's name before her marriage, came from a wealthy and aristocratic
family.

The circus moved on from town to town, and Joe was more and more
satisfied with his purchase of the trained seal. Lizzie in the tank
with Joe was certainly an added attraction. The seal seemed to like the
under-water work as much as Joe did. She ate her fish as Joe ate his
bananas, and was a pretty sight as she cavorted around in the water
with the boy fish swimming by her side.

Joe took frequent rides on his motor-cycle, Helen often accompanying
him, and when one day he found he was able to stay under water for four
minutes and twenty seconds he ascribed his success to his swift riding
in the open air.

"I'll go after the world's record before the season is over," he said
to Helen.

"I hope you make it," she said.

"One thing bothers me, though," said Joe. "I can't use the goldfish in
the tank when I act with Lizzie. She'd do nothing but eat them. And
it's quite a bother to have to take the fish out every time just before
I let Lizzie go into the water. I could have two tanks, I suppose,
doing part of my act in one with the goldfish, and then changing to
another with the seal. But I have enough duffle to cart about as it is.
I don't want another big tank."

"No, it would be a nuisance," agreed Helen.

"I've tried and tried to think of a way to use the double act, but I
can't," Joe went on. "I took a couple of goldfish into the tank with
Lizzie and me one day, but she gobbled them up before I could turn
over. I didn't repeat that experiment."

Helen seemed to be thinking deeply. Suddenly she clapped her hands, her
eyes sparkled, and she cried:

"Oh, Joe! I believe I have it!"

"Have what?"

"The solution of your trouble. I think I know a way in which you can
use the goldfish and the seal in the same tank."

"How, by putting a muzzle on Lizzie?"

"No, but by using a tank with double glass sides. Let me show you what
I mean!"

CHAPTER XX

ACROSS THE TRESTLE

Helen, with a pencil and piece of paper, began rapidly making a little
sketch. Joe looked over her shoulder. They were in the outer section of
the dressing tent, waiting for their turn to go on with their acts.

"See," Helen explained, "you can easily put double glass sides on your
tank by slipping sheets of glass inside the four present outer sides,
leaving a space of five or six inches between them. Fill this space
with wat