which must have consumed several years, and no answer could be
extracted from him.

My habits are methodical, and this has been of not a little use
for my particular line of work. Lastly, I have had ample leisure
from not having to earn my own bread. Even ill-health, though it
has annihilated several years of my life, has saved me from the
distractions of society and amusement.

Therefore my success as a man of science, whatever this may have
amounted to, has been determined, as far as I can judge, by
complex and diversified mental qualities and conditions. Of
these, the most important have been--the love of science--
unbounded patience in long reflecting over any subject--industry
in observing and collecting facts--and a fair share of invention
as well as of common sense. With such moderate abilities as I
possess, it is truly surprising that I should have influenced to
a considerable extent the belief of scientific men on some
important points.