OK, I will admit this may be a weird (if not irrelevant) question but how did they know when “Ice Out” was in 1888 or even 1921 (earliest ice out)? The official ice out criteria is when the Mount can navigate all of its ports. What was the criterion in 1888? They certainly didn’t have the good work of Emerson Aviation, let alone planes. No cars, no phones to coordinate sightings at each port. Did they telegraph each other? Was there some guy going around the lake on a horse everyday (?!?). Probably take a few days just to make it around the lake.
I told you it was a weird question; I was just wondering.