NOVEMBER 19, 1897.] 
I have mentioned, and is still pursued with 
undiminished vigor. Both astronomy and 
astrophysics take their stand on a higher 
plane, where it is a sufficient justification 
for their existence that they enable us better 
to understand the universe of which we 
form a part, and that they elevate the 
thoughts and ennoble the minds of men. 
In considering the importance of astro- 
physical research, I have, therefore, re- 
garded the question from a purely scientific 
point of view. Even with this restriction 
there is room for a considerable diversity of 
opinion, since the elimination of the human 
element from the question is impossible. 
Scientists aremen. Every man is naturally 
inclined to attach special importance to 
that in which he is himself specially inter- 
ested. Personal preferences, or even preju- 
dices, may enter into the estimation in 
which a branch of learning is held. But, 
setting these aside, there are grounds for 
differences of opinion which are entitled to 
respect. What importance is to be at- 
tached, for example, to the proof, now 
brought almost within our grasp by the im- 
provement of spectroscopic instruments and 
methods, that the law of gravity is opera- 
tive within the stellar systems, as well as 
in the system of our own sun? Doubtless 
there are some who are satisfied with the 
moral certainty that we already possess, 
and to whom the proof just mentioned 
would merely afford the satisfaction of ink- 
ing in, on a printed form, the penciled 
words which had already been written in 
its blanks; while there are others who 
would regard the formal proof as alone en- 
titled to consideration. J have even heard 
widely different opinions expressed by emi- 
nent astronomers as to the scientific im- 
portance of a problem so fundamental as 
the exact determination of the distance of 
the sun. 
The degree of importance which we at- 
tach to a newly discovered fact or principle 
SCIENCE. 
747 
is influenced by many circumstances, among 
which we cannot fail to recognize some of 
the failings of human nature. When prog- 
ress is rapid, individual achievements lose 
their prominence, like mountain peaks ris- 
ing from a high plateau. The discovery of 
an asteroid was once a notable event. Now 
it attracts little attention, outside of a 
small circle of observers, and it is probable 
that few of us could say just how many of 
these little bodies have been brought to:light 
during the past year. In astrophysics dis- 
eoveries of the highest significance have 
succeeded one another so rapidly that they 
are now taken as a matter of course. 
The bearings of a discovery on existing 
knowledge are sometimes not immediately 
perceived, and its true scientific impor- 
tanee is not appreciated until these are 
revealed in the fullness of time. Other 
circumstances might be mentioned, but 
these are sufficient for my purpose, which 
is to show that there is no cause for sur- 
prise if opinions differas to the exact value 
of astrophysical research. It is because 
the science of astrophysics is so young—so 
distinctly in the formative stage—that I 
have ventured to discuss a question which, 
in due time, will settle itself. 
A feature of astrophysical research which 
I do not wish to leave unmentioned is the 
interest which is felt in it by the public. 
Those who are interested in the resuits of 
science, but who care little for methods, 
and know nothing of elegant forms of an- 
alysis, are naturally more attracted by the 
view of the heavenly bodies which astro- 
physies presents than by the view which 
is obtained from the standpoint of the 
older astronomy. Astrophysics paints its 
picture in the brighter colors. A star re- 
garded as a center of attraction, or as a 
reference point from which to measure ce- 
lestial motions, awakens little enthusiasm 
in the popular mind; but a star regarded 
as @ sun, pouring out floods of light and 
