5 
of some of the more prominent branches of 
science. Thus, double stars seem to be orbs 
analogous to our own sun, revolving round 
their common centre of gravity, in such a 
manner as that gravitation would appear not to 
be limited to the Solar System, but to extend 
to such systems of stars. Doubt, indeed, has 
been expressed whether gravitation acts yvith. 
the nebulae — at least those of a spiral form — as 
it does with us ; possibly some other modifying 
influence may exist, our ignorance of 
which gives rise to the doubt. Again, 
there is evidence, almost amounting to 
proof, that meteors or shooting stars 
are cosmical bodies, moving in the 
interplanetary space by gravitation round 
the sun, and some, perhaps, round planets. 
This view gives us a new element of continuity. 
The universe would thus appear not to have 
the extent of empty space formerly attributed 
to it, but to be studded between the larger and 
more visible masses with smaller planets, if the 
term be permitted to be applied to meteorites. 
Further, the number of known asteroids, or 
bodies of a smaller size than what are termed 
the ancient planets, has been so increased by 
numerous discoveries that, instead of seven, we 
now count eighty-eight as the number of re- 
cognised planets, the smallest of which is only 
three or four miles in diameter. Were we to 
apply the same scrutiny to other parts of the 
heavens, as has been applied to the zone be- 
tween Mars and Jupiter, it is no far-fetched 
speculation to suppose that, between these 
asteroids and the meteorites, bodies of inter- 
mediate size exist until the space occupied by 
our Solar System becomes filled with planetary 
bodies, varying in size from that of Jupiter 
(1240 times larger in volume than the earth), 
to that of a cannon ball or even a pistol bullet. 
According to M. Daubree, the similarity of 
terrestrial rocks to meteorites increases as we 
penetrate deeper into the earth’s crust, and 
some of the deep-seated minerals have a com- 
position and characteristics almost identical 
with meteorites ; and, by experiments, he has 
succeeded in forming, from terrestrial rocks, 
substances very much resembling meteorites. 
Thus close relationship, though by no means 
identity, is established between this earth and 
those wanderers from remote regions ; some 
evidence, though at present incomplete, of a 
common origin. Mr. Grove adds that it has 
long seemed to him that there is no ground for 
wonder that, while the mean specific gravity of 
this globe is from five to six times that of 
water, that of its crust is barely half as great. 
The exterior is to a considerable depth 
oxidated ; the interior is, in all probability 
free from oxygen, and whatever bodies exist, 
there, are in a reduced or deoxidated stats — if 
so, their specific gravity must necessarily be 
higher than that of their oxides, chlorides, &c. 
Next, optical Bcience aids us in inquiring into 
the relation of our planet in composition to 
other planets, to the sun, and to more distant 
suns and systems. Light, passing from one 
transparent medium to another, carries with it 
evidence of the source from which it emanates, 
and, probably (could we read it) everything 
contains in itself a large portion of its own 
history. The spectrum analysis seems to show 
that, while comparatively neighbouring cos- 
mical bodies exhibit lines identical with those 
shown by the components of this planet, as we 
proceed to the more distant appearance of the 
nebulae we get but one or two of such lines, and 
we get one or two new bands not yet identified 
with, any known to be produced by substances 
on this globe. The position in the spectrum 
of the bright line furnished by the nucleus of 
the comet 1 of 1866 is the same a3 that of 
nitrogen, whieh is also shown in some of the 
nebuke, but its coma or tail, apoeared to be in 
a condition analogous to that of fog or cloud. 
The temporary star which shone forth 
this year in the constellation of the Northern 
Crown gave a spectrum alleged to be unlike that 
of any celestial body before examined. One 
of its spectra was analogous to that of the sun. 
The second indicated that the light was emitted 
by luminous gas, probably hydrogen at a very 
high temperature and burnt with some other 
element, and that by the resulting temperature 
the photosphere was heated to incandescence. 
It would seem as if the phenomenon of gradual 
change obtained towards the remotest of known 
objects, and that the further we penetrate into 
space the more unlike to those with which we 
are acquainted become the objects of our 
examination. Whether the moon has even a 
minute atmosphere, and whether certain por- 
tions of her surface are indicative of igneous 
fusion or of diluvial formation, are points on 
which at present no positive opinion can be 
pronounced. There seems to be room for a 
substantial improvement in the construction of 
the achromatic telescope. Passing on to the 
subject of, what are sometimes called, the im- 
ponderables, Mr. Grove says that magnetism 
and electricity are forces so universal, so 
apparently connected with matter as to be- 
come two of its invariable attributes, and so 
with light, heat, and chemical affinity. It 
seems to him that it is now proved that all 
these forces are so invariably connected with 
each other and with motion, as to be regarded 
as modifications of each other, and as resolv- 
ing themselves objectively into motion, and 
subjectively into that something which pro- 
duces or resists motion, and which we call force. 
Magnetism, then, must be cosmical and not 
merely terrestrial ; and to trace it in other 
planets and suns as a force manifested in axial 
or meridional lines would be a great, but it is 
a hitherto unaccomplished, step. Mr. Grove 
then observes that one of the most startling 
suggestions as to the consequence resulting 
from the dynamical theory of heat is that made 
by Mayer, that by the loss of vis viva ocoa- 
