Princeton and Williston Academy invade the I.A.B. pool at 8:30 and 7:15 p.m. tonight to give the undefeated varsity and Yardling swimming teams their strongest home opposition of the season. The Tigers rank fourth in the Eastern Intercollegiate League, while Williston stands first in secondary school swimming, having barely lost to the Yale freshmen.

Princeton, varying from hot to cold, edged Navy, 43 to 41, and dropped Penn, 56 to 28. The Crimson scored more points against both of these teams and also downed Army and Dartmouth, to whom the Tigers lost.

For Princeton, this is a letter meet; a Tiger must score against the Crimson or Yale to win his "P". Free stylers Captain Ed Breisacher, Jay Evans, John Gray, Owen Jacobsen, Dave Johnson, and Denny Rice are all sure of placing.

Ulen Fears Let-Down

Sophomore Evans is an excellent sprinter, and either Breisacher or Gray will combine with back stroker Bill O'Brien and breast stroker Jim Sidford to form a good medley relay team. Tiger divers John Skvaria and Jack Coogan are rated about equal to the Crimson.

Coach Hal Ulen fears a post-Dartmouth let-down for his varsity, and Bill Brooks is also worried about the opposition for his freshmen. Williston, defending national scholastic champion, has three record-breakers on its squad. Clip Ide in the sprints. Larry Scheescher in the individual medley, and Ed Peterson in the back stroke all have broken Academy marks.