I have one observation from late August, 1993 (with my old 20-inch Obsession) when the globular was low on the western horizon:

"Neat globular - rather large and showed a hint of resolution at 182x and averted vision. Embedded in a triangle of field stars, this too was very low and I watched it set behind the trees at 182x - very cool!"

I'd just observed NGC 4866 only 3 degrees above the western horizon where I commented "this is really clear air!"