The Sun.
London, England, 1861-09-05 00:00:00

guished philosephers. Tycho Brahe, by his system of accu-
rate measurement of the position of the heavenly bodies ;
Copernicus, by his history of the solar system ; Galileo, by
the application of the telescope ; and Kepler, by the dis-
covery of the laws of the planetary motions, all assisted in
advancing, by prodigious strides, towards a true knowledge
of the constitution of the universe. It remained for New-
ton to introduce at a later period the idea of an attraction
varying directly as the mass, and inversely as the square of
the distance, and thus to reduce celestial phenomena to the
greatest simplicity by comprehending them under a single
law. Without tracing the details of the history of this

science, we may notice that in more recent times astrono-
mical discoveries have been closely connected with high
mechanical skill in the construction of instruments of pre-
cision. The telescope has enormously increased the cata-

Logue of the fixed stars, or those ' landmarks of the uni-

verse,' as Sir John Herschel terms them, ' which never
deceive the astronomer, navigator, or surveyor.' The num-
ber of known planets and asteroids has also been greatly

enlarged. The discovery of Uranus resulted immediately
from the perfection attained by Sir Wm. Herschel ill the
construction of his telescope. ' More recently the structure

of the nebulae has been unfolded through the application
to their study of the colossal telescope of Lord Rosso. In

all these directions much has been done both by our pre- •

sent distinguished Astronomer Royal, and also by amateur
observers in private observatories, all of whom, with Mr.
Lassells at their head, are making rapid advances in this

department of physical science.- Our knowledge of the
physical constitution of the central body of our system
seems likely, at the present time, to be much increased.
The spots on the sun's disc were noted by Galileo and
his contemporaries, and enabled them to ascertain the
time of its rotation, and the inclination of its axis.

They also correctly inferred, from their appearance, the
existence of a luminous envelope, in which funnel-
shaped depressions revealed a solid and dark nucleus. Just a
century ago, Alexander Wilson indicated the presence of a
second and less luminous envelope beneath the outer stra-

turn, and his diseovery was confirmed by Sir W. Herschel,
who was led to assume the presence of a double stratum of
clouds, the upper intensely luminous, the lower gray, and
forming the penumbra of the spots. Observations during
eclipses have rendered probable the supposition that a third
and outermost stratum of imperfect transparency encloses
concentrically the other envelopes. Still more recently the
remarkable discoveries of Kirchoff and Bunsen require us
to believe that solid or liquid photosphere is seen through
an atmosphere containing iron, sodium, lithium, and other
metals in a vaporous condition. We must still wait for the
application of a more perfect instrument, and especially for
the careful registering of the appearances of the sun by the
photoheliograph of Sir John Herschel, so ably employed
by Mr. Warren de la Rue,•Mr.Welsh, and others, before we
can expect a solution of all the problems thus suggested.
Guided by the same principles which have been so success-
ful in astronomy, its sister science, magnetism, emerging
from its infancy, has of late advanced rapidly in that stage
of development which is marked by assiduous and sys-
tematic observation of the phenomena, by careful analysis
and presentation of the facts which they disclose, and by the
grouping of these in generalisation, which, when the basis
on which they rest shall be more extended, will prepare the
way for the conception of a general physical theory, in
which all the phenomena shall be comprehended, while
each shall receive its separate and satisfactory explanation.
It is unnecessary to remind you of the deep interest which
the British Association has at all times taken in the ad-

vancement of this branch of natural knowledge, or of the
specific recommendations which, made in conjunction with
the Royal Society, have been productive of such various
and important results. To refer but to a single instance,
we have seen those magnetic disturbances, so mysterious
in their origin and so extensive in simultaneous prevalence
—and which. less than 20 years ago, were designated by a
term specially denoting that their laws were wholly un-
known—traced to laws of periodical recurrence, revealing,
without a doubt, their origin in the central body of our sys-
tem, by inequalities which have for their respective periods
the solar day, the solar year, and, still more remarkably, an
until lately unsuspected solar cycle of about ten of our ter-
restrial years, to whose existence they bear testimony in
conjunction with the solar spots, but whose nature and
causes are in all other respects still wrapped in entire ob-
scurity. We owe to General Sabine, especially, the recog-
nition and study of these and other solar magnetic influ-
ences, and of the magnetic influence of the moon similarly
attested by concurrent determinations in many parts of the
globe, which are now held to constitute a distinct branch
of this science not inappropriately named ' celestial,' as dis-
tinguished from purely terrestrial magnetism. We ought
not in this town to forget that the very rapid advance
which has been made in our time in chemistry is due to the
law of equivalents, or atomic theory, first discovered by our
townsman, John Dalton. Since the development of this
law its progress has been unimpeded, and it has had a most
direct bearing on the comforts and enjoyments of life. A
knowledge of the constituents of food has led to important
deductions as to the relative nutritive value and com-
mercial importance of different materials. Water has been
studied in reference to the deleterious impurities with which
it is so apt to be contaminated in its distribution to the in-
habitants of large towns. The power of analysis, which
enables us to detect adulterations, has been invaluable to
the public health, and would be much more so if it were
possible to obviate the difficulties which have prevented the
operation of recent legislation on this subject. We have
another proof of the utility of this science in its application
to medicine ; and the estimation in which it is held by the
medical profession is the true index' of its value in the diag-
nosis and treatment of disease. The largest developments
of chemistry, however, have been in connection with the
useful arts. What would now be the condition of calico -
printing, bleaching, dyeing, and even agriculture itself, if
they had been deprived of the aid of theoretic chymistry l'
For example, aniline—first discovered in coal tar by Dr.
Hoffman, who has so admirably developed its properties—
is now most extensively used as the basis of red, blue, vio-
let, and green dyes. The important discovery will probably
in a few years render this country independent of the world
for dye stuffs ; and it is more than probable that England,
instead of drawing her dye stuffs from foreign countries may
herself become the centre from which all the world will be
supplied. It is an interesting fact that at the same time in
another branch of this science M. Tournet has lately de-
monstrated that the colours of gems, such as the emerald,
aqua-marina, amethyst, smocked rock crystal, and others,
are due to volatile hydro-carbons, first noticed by Sir David
Brewster in clouded topaz, and that they are not derived
from metallic oxides, as has been hitherto believed. Another
remarkable advance has recently been made by Bunsen and
Kirchoff in the application of the coloured rays or the
prism to analytical research. We may consider their dis-
coveries as the commencement of a new era in analytical
chemistry, from the extraordinary facilities they afford in
the qualitative detection of the minutest traces of elementary
bodies. The value of this method has been proved by the
discovery of the now metals cmsium and rubidium by M.
Bunsen, and it has yielded another remarkable result in de-
monstrating the existence of iron and six other known
metals in the sun. In noticing-the more recent discoveries
in this important science I must not pass over in silence
the valuable light which chemistry has thrown upon the
composition of iron and steel. Although Despretz demon-
strated many years ago that iron would combine with nitro-
gen, yet it was not until 1857 that Mr. C. Binks proved
that nitrogen is an essential element of steel, and more re-
cently M. Carou and M. Fremy have further elucidated this
subject; the former showing that cyanogen, or cyanide of
ammonium, is the essential element which converts wrought
iron into steel ; the latter combining iron with nitrogen
through the medium of ammonia, and then converting it
into steel by bringing it at the proper temperature into
contact with common coal gas. There is little doubt that
in a few years these discoveries will enable Sheffield manu-
facturers to replace their present uncertain, cumbrous, and
expensive process by a method at once simple and inexpen-
sive, and so completely under control as to admit of any re-
quired degree of conversion being obtained with absolute
certainty. Mr. Crace Calvert, also, has proved that cast
iron contains nitrogen, and has shown that it is a definite
compound of carbon and iron mixed with various propor-
tions of metallic iron, according to its nature. Before
leaving chemical science, I must refer to the interesting
discovery by M. Deville, by which he succeeded in rapidly
melting 38 or 40 pounds of platinum—a metal till then consi-
dered almost infusible. This discovery will render the ex-
traction of platinum from the ore more perfect, and, by re-
ducing its cost, will greatly facilitate its application to the
arts. It is little more than half a century since geology as-
sumed the distinctive character of a science. Taking into
consideration the aspects of nature in different epochs of the
history of the earth, it has been found that the study of the
changes at present going on in the world around us enables
us Cr. understand the past revolutions of the globe, and the
conditions and e:eceresteeses under which strata have been
formed and organic remains entutd,l,l and preserved. The
geologist has increasingly tended to believe that the elating-es
which have taken place on the face of the globe, from the
earliest times to the present, are the result of agencies still
at work. But while it is his high office to record the dis-
tribution of life in past ages, and the evidence of physical
changes in the arrar gement of land and water, his results
hitherto have indicated no traces of its beginning, nor have
they afforded evidence of the time of its future duration.
Geology has been indebted for this progress very largely to
the investigations of Sedgewick and the writings of Sir
Charles Lyall. As an example of the application of geology
to the practical uses of life, I might cite the discovery of
the goldfields of Australia, which might long have remained
hidden but for the researches of Sir Roderick Murchison in
the Ural Mountains on the geological position of the strata
from which the Russian gold is obtained. From this inves-
tigation he was led by inductive reasoning to believe that
gold would be found in similar rocks, specimens of which
had been sent him from Australia. The last years of the
active life of this distinguished geologist have been devoted
to the re-examination of the rocks of his native Highlands
of Scotland. Applying to them those principles of classifi-
cation which he long since established, he has demon-
strated that the crystalline limestone and quartz rocks
which are associated with mica schists, &c., belong by their
embedded organic remains to the Lower Silurian Rocks.
Descending from this well-marked horizon, he shows the
existence beneath all such fossiliferous strata of vast masses
of sandstone and conglomerate of Cambrian age ; and, lastly,
he has proved the existence of a fundamental Gneiss, on
which all the other rocks repose, and which, occupying the