11 
14th of July, I860, at Dhurmsalla, in the 
Punjab. The cold of the fragments that fell 
waB so intense as to benumb the hands of the 
coolies who picked them up, and who were 
obliged, in consequence of their coldness, 
instantly to drop them. With respect to the 
acceleration of the moon’s mean motion, I 
would observe that it may perhaps be regarded 
as demonstrated by MM. Delauuay, Airy and 
Adams that the action of the sun and moon on 
the tidal protuberance generates such an 
amount of friction as Blightly to retard the 
earth’s diurnal rotation on its axis. The whole 
augmentation in the length of the day required 
is at the continuous rate of only one second of 
time in two hundred thousand jears. Incon- 
ceivably small as is this amount of alteration 
in the length of the day, its effect on the 
moon’s place could not be overlooked by a 
skilful observer of the present day. Perhaps, 
as has been justly said, herein we may recog- 
nise the highest and most successful effort of 
the human mind, or rather (as in truth it is) 
the combined efforts of a succession of minds. 
The final consequence of this diminution of the 
length of the day would be, says Helmholtz, 
but after millions of years — if, in the mean- 
time, the ocean did not become frozen — that 
one side of the earth would be constantly 
turned towards the sun, and enjoy a perpetual 
day, whereas the opposite side would be 
involved in eternal night. Such a 
position we observe in our moon 
with regard to the earth, and also iu the case 
of satellites as regards their planets, It is, 
perhaps, due to the action of the mighty ebb 
and flow to which these bodies, in the time of 
their fiery fluid condition, were subjected. 
From a contemplation of the planetary bodies 
we may arrive at fresh illustrations of con- 
tinuity, aud at conclusions with reference to 
the past as well as the probable future of our 
own earth. A number of singular peculiari- 
ties in the structure of our planetary system 
indicate that it was once a connected mass 
with a uniform motion of rotation. Without 
such an assumption it is impossible to explain 
why all the planets move in the same direction 
round the sun, why they all rotate in the same 
direction round their axes, why the planes of 
their orbits, and those of their satellites and 
rings, all nearly coincide, why all their orbits 
differ but little from circles, and much be- 
sides. From these remaining indications of a 
former state astronomers have shaped an hy- 
pothesis regarding the formation of our 
planetary system, which, although from the 
nature of the case it must ever remain an 
hypothesis, still in its special traits is so well 
supported by analogy that it certainly deserves 
attention. It was Kant who, feeling great 
interest in the physical description of the earth 
and the planetary system, undertook the 
labour of studying the works of Newton, and, 
as ^an evidence of the depth to which he had 
penetrated into the fundamental ideas of 
Newton, seized the notion that the same at- 
tractive force of all ponderable matter which 
now supports the motion of the planets must 
also, aforetime, have been able to form, from 
matter loosely scattered in space, the planetary 
system. Afterwards, and independently of 
Kant, Laplace, the great author of the Afe- 
canique Celeste laid hold of the same thought, 
pud introduced it among astronomers. Tho 
commencement of our planetary system, 
including the sun, must, according to 
this, be regarded as an immense nebulous 
mass that filled the portion of space which 
is now occupied by our system, far beyond the 
limits of Neptune, our most distant planet. 
Even now, perhaps, we see similar masses in the 
distant regions of the firmament, as patches of 
unresolved nebulae, or unresolved nebulous 
stars j within our system, also, comets, the 
zodiacal light, the corona of the sun during a 
total eclipse, exhibit remnants of a nebulous 
substance, which is so thin that the light of 
the planets passes through it uuenfeebled and 
unrefracted. If we calculate the density of the 
mass of our planetary system, according to the 
above assumption, for the time when it was a 
nebulous sphere, which reached to the path of 
the outermost planet, we should find that it 
would require several cubic miie9 of such 
matter to weigh a single grain. The general 
attractive force of all matter must, however, 
have impelled these masses to approach 
each other, and to condense, so that the nebu- 
lous sphere became incessantly smaller, by 
which, according to mechanical laws, a motion 
of rotation originally slow, and the existence of 
which must be assumed, would gradually be- 
come quicker and quicker. By the centri- 
frugal force, which must act most energetically 
at the equator of the nebulous sphere, masses 
could from time to time be torn away, which 
afterwards would continue their courses 
separate from the main mass, forming them- 
selves into single planets, or, similar to the 
great original sphere, into planets with 
satellites and rings, until finally the principal 
mass condensed itself into the sun. Iu this 
theory all that is hypothetical is the assumption 
of Kant and Laplace, that the masses of our 
system were once distributed as nebulae in 
space. I have, in the above brief ex- 
planation of it, followed almost ex- 
actly the translated words of Helm- 
holtz. His account is much more sum- 
mary than that of Laplace, and perhaps 
requires expansion. In some future communi- 
cation to this Society I hope to give a fuller 
account of the theory, and, in connection with 
it, to notice certain researches of Mr. Haughton 
and M. Babinet. At present I conclude with 
stating that Helmholtz, speaking of this theory 
of the origin of the solar system, remarks in 
what close coincidence the results of science 
here stand with the earlier legends of the 
