March 27, 1897: I can't really tell what the sport is in this issue as the picture depicts just a group of boys similarly dressed in what looks like maybe a boathouse having a confrontation. So my inclination is to say this is like a crew uniform, perhaps? Most likely a boat sport of some kind.
Frank has a lot of similar outfits to this: long-sleeved Yale blue knit tops and white shorts ~ basic all-purpose sport clothing. The "Y" is pretty ubiquitous on almost all of these.
Patten, who wrote the series, never went to Yale, but apparently did his research.