A couple of tennis balls were flying around in the tank and the newcomers were soon taking their parts in the fun.

Presently the group of older fellows, having grown tired of guying the "kids," dived into the water.

Getting possession of one of the balls, they tried to keep it to themselves, and soon there was a merry and good-natured battle on between the five big chaps on one side and the younger occupants of the tank on the other.

The echoing room rang with laughter and excited cries as the contending sides swam and floundered for the possession of the tennis ball.

The big chaps had their hands full, for they were outnumbered four to one, but age and strength counted for them and not infrequently a youngster, rather than undergo a ducking at ungentle hands, yielded the ball and swam away with squeaks of terror.