Posted By:
Donald JohnsonJoann,
The 91 represents the graduating class year. I believe this to be a shot of the incoming "freshman" class in 1887. As to why some of the jersey's have H's and some don't, I don't remember exactly; either it had to do with some positions having different uniforms or perhaps the guys in the photo just showed up in different uniforms
. There's a matching Yale cabinet up for sale on Ebay right now (not as well preserved as this one. You can see much of the same disparity in uniforms in that photo as well.