f this group of men was
Professor Peirce, mathematician, of whose flights into the higher
regions of the science of numbers and quantities many interesting
things were told. He had written a book to show, if I remember right
after so many years, that the square root of minus one was a right
angle

__
(\/-1=90 deg.),

which was said to have been read only by a mathematician who presided
over an observatory in the Ural Mountains. He had an extraordinary
power of making his abstruse results clear to the ordinary intellect,
and was in various directions a brilliant conversationalist. One day,
going into Boston in the omnibus with him, I questioned him as to the
famous problem. To my astonishment he went through a demonstration
adapted to my intelligence which made me understand the nature of
the substitution and the solution before our half hour's transit was
ended. I did not understand the mathematical statement, but he put it
in common-sense terms, which I apprehended perfectly, though I never
could repeat them.

My Adirondack experiences and studies having excited the desire on the
part of several Cambridge friends to visit the Wilderness, I made up
a party which comprised Lowell and his two nephews, Charles and James
Lowell (two splendid young New Englanders afterwards killed during the
Civil War), Dr. Estes Howe, Lowell's brother-in-law, and John Holmes,
the brother of Oliver Wendell, considered by many of the Cambridge set
the wittier and wiser of the two, but who, being extremely averse to
publicity, was never known in literature. We made a flying journey of
inspection through the Saranac Lakes and down the Raquette River
to Tupper's Lake, and then across a wild and at that day a little
explored section to the head of Raquette Lake, and down the Raquette
River back to the Saranacs; the party returning home and I back to the
headwaters of the Raquette to spend the summer painting. I built a
camp on a secluded bay, which still bears my name amongst the men of
the section, and there I worked in a solitude sometimes complete and
sometimes shared by my guide, who passed his time between the camp and
the settlement at Saranac, whence I drew all my supplies beyond those
which the lake and the forest furnished us with. The solitude of the
Wilderness at that time can be no longer found anywhere in the vast
woodland which, much mutilated and scarred by fires and clearings,
still covers the district between the spri