etween the
color of Aldebaran and the whitest star." No further research was
necessary. For half a century the astronomical world had based an
impression on the innocent but mistaken evidence of a color-blind
man--respecting the tints of ink in a manuscript.

It has doubtless happened more than once that when an intimate friend
has suddenly and unexpectedly passed away, the reader has ardently
wished that it were possible to whisper just one word of appreciation
across the dark abyss. And so it is that I have ever since felt that I
would like greatly to tell Father Hell the story of my work at Vienna
in 1883.

XVI

THE EVOLUTION OF THE SCIENTIFIC INVESTIGATOR

[Footnote: Presidential address at the opening of the International
Congress of Arts and Science, St. Louis Exposition, September 21: 1904.]

As we look at the assemblage gathered in this hall, comprising so many
names of widest renown in every branch of learning--we might almost say
in every field of human endeavor--the first inquiry suggested must be
after the object of our meeting. The answer is that our purpose
corresponds to the eminence of the assemblage. We aim at nothing less
than a survey of the realm of knowledge, as comprehensive as is
permitted by the limitations of time and space. The organizers of our
congress have honored me with the charge of presenting such preliminary
view of its field as may make clear the spirit of our undertaking.

Certain tendencies characteristic of the science of our day clearly
suggest the direction of our thoughts most appropriate to the occasion.
Among the strongest of these is one towards laying greater stress on
questions of the beginnings of things, and regarding a knowledge of the
laws of development of any object of study as necessary to the
understanding of its present form. It may be conceded that the
principle here involved is as applicable in the broad field before us
as in a special research into the properties of the minutest organism.
It therefore seems meet that we should begin by inquiring what agency
has brought about the remarkable development of science to which the
world of to-day bears witness. This view is recognized in the plan of
our proceedings by providing for each great department of knowledge a
review of its progress during the century that has elapsed since the
great event commemorated by the scenes outside this hall. But such
reviews do not make up that general survey of science