Princeton University's Cannon Exercises, ca. 1897.
Cannon Exercises were once part of Commencement Week celebrations, and happened on Class Day. Students would gather for lighthearted speeches, then smoke clay pipes and smash them against the cannon (a relic of the Revolutionary War's Battle of Princeton, which is "planted" upright on Cannon Green behind Nassau Hall). Here, you can see the cannon decorated with flowers for the occasion.
Illustration from James W. Alexander's Princeton--Old and New: Recollections of Undergraduate Life (1898).












