Sure enough, if you click to zoom in you can see several small buildings in the most heavily wooded section along Harris Gully, near where Reckling Field is today. I can’t see everything because of the trees but the structures that I do see seem to line up with the blueprint that originally got me going on this.
I’m pretty satisfied with this answer because it generally makes sense. What bothered me was this: how could I not have noticed an entire group of buildings that existed for decades on a small campus? The answer is 1) none of the people who left papers behind had any interest in talking about this, being preoccupied with things like building an academic institution and 2) there are very few images that show this relatively empty part of campus in this era. Quite sensibly, people who were making photographs wanted pictures of the impressive buildings rather than mule sheds. So, it adds up.
This is an interesting picture in many other ways and I’ll give it much further study. Just for one example, you can really clearly see the curved line where the railroad spur had been. And are those row crops in the area to the right of the mule sheds??