I've been working on a slideshow for chapter 19 from The Innocents
Abroad.  The chapter contains some interesting observations on art
critics and their perceptions, particularly in regards to The Last
Supper.  There is, however, another observation made by Twain, a single
paragraph describing an unattributed painting.  I was wondering if
anyone can identify the painting and artist and if an image of the
painting exists on-line anywhere.  The paragraph reads:

"In another place we were shown a sort of summer arbor, with a fence
before it. We said that was nothing. We looked again, and saw, through
the arbor, an endless stretch of garden, and shrubbery, and grassy lawn.
We were perfectly willing to go in there and rest, but it could not be
done. It was only another delusion—a painting by some ingenious artist
with little charity in his heart for tired folk. The deception was
perfect. No one could have imagined the park was not real. We even
thought we smelled the flowers at first."