The evening telegraph. [volume] (Philadelphia [Pa.]) 1864-1918, 1869-09-29

At the inaugural meeting of the British
Association for the Advancement of Science I
held in Exeter, England, last month, Prof.
stokes. President elect, made an excellent
address upon some of the leading phases of
scientific research. He first spoke of
PROGRESS IN ASTRONOMICAL SCIENCE.
Among the various branches of physical
science. Astronomy occupies in many respects
a foremost rank. The movements OF the
heavenly bodies must have occupied the atten-
ton and excited the interest of mankind from
the earliest ages, and accordingly the first
rudiments of the science are lost in the
depths of antiquity. The grandeur OF the
subjects of contemplation which it presents
TO us have won for it especial favor, and its
importance in relation to navigation has
caused it to be supported by national re-
sources. Newton's great discovery OF unlver-
sal gravitation raised it from the rank OF
science of observation to that of one admit
tino of the most exact mathematical deduc-
ton; and the investigation of the conse-
uuences of this law, and the explanation
thereby of the lunar and planetary disturb
ances have afforded field for the exercise of
the highest mathematical powers on the part
of Newton and his successors. Gradu-
ally the apparent anomalies as they might
have been deemed, in the motions of
the heavenly bodies were shown to be
necessary consequences of the one fundamen-
tai law; and, at last, as the result of calcula-
tions of enormous labor, tables were con-
structed enabling the places Of those bodies
at any given time to be determined years be-
forehand with astonishing precision. A still
more striking step was taken When it had
been shown by careful calculation that the
apparent motion of the remotest of the
planets then known to belong to our system
could not be wholly explained on the theory
of gravitation, by taking account Of the dis
turbing powers of the other known planets,
Adams in our own country, and lie
Verrier in France, boldly reversed the
problem, and instead of determining the
disturbing effect of known planet, set
themselves to inquire what must be the
mass and orbit of an unknown planet which
shall be capable of producing by its disturbing
force the unexplained deviations in the posi-
ton of Uranus from its calculated place. The
result of this inquiry is too well known to
require notice.
After these brilliant achievements, some
may perhaps have been tempted to imagine
that the field of astronomical research must
have been wellnigh exhausted. Small pertur-
bations, hitherto overlooked, might be deter
mined, and astronomical tables thereby
rendered still more exact. New asteroids
might be discovered by the telescope More
accurate values of the constants with which
we have to deal might be obtained. But no
essential novelty of principle was to be looked
for in the department of astronomy; for such
we must go to younger and less mature
branches of science.
FRUITS OF THE UNION OF SCIENCES.
Researches which have been carried on
within the last few years, even the progress
which has been made within the last twelve
he Gl,A,., l.N.,,
patton would have been; what an unexpected
flood of light may sometimes be thrown over
one science by its union with another; how
conducive accordingly to the advancement of
science may be an Association like the pre-
sent, in which not only are the workers at
special meetings brought together in the Sec
tional Meetings, but in the General Meetings
of the Association, and in the social inter
course which, though of an informal charac-
ter, is no unimportant part of our proceedings,
the cultivators of different branches of sci
ence are brought together and have an oppor-
tunity of enlarging their minds by contact
with the minds of others, who have been
used to trains of thought of very different
character from their own.
WHAT ASTRONOMY OWES TO OPTICS.
~-Tba rcio3nnce of astronomy is indebted to
that Of Optics for the princnr..ees which regu-
late the construction of those optical ineSir9-
ments which are so essential to the astrono-
mer. 1t repaid its debt by furnishing to
optics result which it is important we
should keep in viewin considering the nature
of light. 1t is to astronomy that we are in
debted for the first proof we obtained of the
finite velocity of light, and for the first nu-
merical determination of that enormous
velocity. Astronomy, again, led, forty-four
years later, to a second determination of that
velocity in the remarkable phenomenon of
alteration discovered by Bradley, phe-
nomenon presenting special points of
interest in relation to the nature of
light, and which has given rise to some dis
cussion, extending even to the present day, so
that the Astronomer Royal has not deemed it
unworthy of investigation, laborious as he
foresees the trial is likely to prove, to deter
mine thesconstant of alteration by means of
a telescope having its tube filled with water.
If in respect of these phenomena optics
received much aid from astronomy, the latter
science has been indebted to the former for
information which could not otherwise have
been obtained. The motions and the masses
of the heavenly bodies are revealed to us
more or less fully by astronomical OBJ
seryations; but we could not thus be,
come acquainted with the chemical nature
,pf these distant, objects. Yet, by the
application Of the spectroscope to the
scrutiny of the heavenly bodies, evidence has
been obtained of the existence therein of
various elements known to us by the chemi.
cal examination of the materials of which on,
own earth is composed; and not only SO. but
l;oht is thrown on the state in which matter i,
there existing, which, in the case of nebula
especially, led to the formation of new idea
respecting their constitution, and the recti