98 
THE FOUNDATIONS OF THE EARTH. 
[Nature and Art, April 1, 1867. 
thickly clustered as to affect the eye only by their 
united lustre — -just as a handful of sand thrown on 
the floor would look only like a dusky patch to an 
eye so distant that it could not perceive the 
individual grains. Some of them were clearly 
resolvable into their component stars with high 
telescopic power, and it was thought that a sufficient 
increase of optical power would resolve the whole 
of them. But as his familiarity with their features 
increased, he was led to an opinion analogous to 
that of some of the older astronomers : that was, 
that they were immense heaps of some vapoury or 
elementary matter out of which stars were, in the 
course of countless ages, formed by a process of 
condensation, such as the attraction of one pai’ticle 
by another would produce. With this theory in 
his mind he was led to classify the various 
descriptions of nebulse that had passed in review 
before him, according to a plan or scheme of pro- 
gressive development : sorting together into one 
grade all those of a certain extent of diffusion, and 
those of a more condensed nature into another. 
His first class included the extensively diffused and 
shapeless nebulosities that are faintly discernible 
and traceable over large areas of celestial space; 
his second embraced those that exhibited a stage a 
little more approaching a regular form ; and so on 
through about thirty classes, the latter of which 
included those in which the condensation had 
proceeded so far as to give them the appearance of 
planets or nebulous stars. Between the descriptions 
of the members of one class and those of another, 
there was not a greater difference than — to quote 
his own words — “ there would be in an annual 
description of the human figure were it given from 
the birth of a child till he comes to be a man in his 
prime.” He further adds : — “ the total dissimi- 
litude between the appearance of a diffusion of the 
nebulous matter and of a star, is so striking, that 
an idea of the conversion of the one into the other 
can hardly occur to any one who has not before him 
the result of the critical examination of the 
nebulous system which has been displayed in this 
(his) paper.' The end I have had in view, by 
arranging my observations in the order in which 
they have been placed, has been to show, that the 
above-mentioned extremes may be connected by 
such nearly allied intermediate steps as will make 
it highly probable that every succeeding state of 
the nebulous matter is the result of the action of 
gravitation upon it, while in a foregoing one, and 
by such steps the successive condensation of it has 
been brought up to the planetary condition.” 
The observations of Herschel paved the way for 
the speculations of the illustrious Laplace. 
Herschel, from the evidence afforded by his ob- 
servations, explained how, by the mere action of 
gravitation, a chaotic mass of primordial matter was 
probably transformed into a body of definite form 
and dimensions, though still of a somewhat diffused 
and nebulous nature : Laplace demonstrated how 
the known laws of gravitation could, from such a 
planetary mass of diffused matter’, produce a system 
of bodies revolving about a great central one, such 
as we have an example of in our solar system. 
This theory has ever since been known as Laplace’s 
nebular hypothesis. When its illustrious author 
put forth his conjectures he did so, to use his own 
words, “ with the deference that ought to inspire 
everything that is not a result of observation and 
calculation ; ” at the same time he expressed his 
conviction that the striking coincidences of all the 
planetary phenomena with the conditions of his 
hypothesis, gave his conjectures a probability 
strongly approaching certitude. 
It is not easy to give an intelligible description 
of such an intricate subject as the nebular hypo- 
thesis within the limited confines of a popular 
article ; nor is it necessary : those who wish to 
pursue it in all its details will hardly resort to a 
periodical like ours for their information, as they 
know, or would soon learn, where to find the 
original work in which it was put forth. All that 
is necessary, is to give the reader such few of the 
leading features of the theory as will suffice to 
explain its principle. 
Laplace supposed, then, that the whole solar 
system was once a huge nebula, with a slight con- 
densation in the centre, like many which we now 
find scattered about the heavens ; and that it was 
endued with a rotary motion around its centre. 
(It must be borne in mind that a nebula as 
extensive as the limits of the solar system would be 
a very small one compared to many hundreds of 
those that are known.) He supposed that in the 
process of condensation, combined with the effect 
of the rotary motion, this nebula threw off or 
abandoned certain of its outlying portions from 
time to time : first throwing off a zone or ring of 
matter which was to form the remotest planet of 
our system — Neptune : then condensing a little 
more and casting off a second, within the former, 
which was to form the next planet — Uranus : then a 
third to form Saturn ; a fourth to form J upiter ; a fifth 
to form Mars ; a sixth to form the earth, and so on. 
These various concentric rings or zones of matter, 
he supposes, themselves broke up and condensed 
and formed little nebulse, revolving about the 
central one which Was left when all the above 
were cast off, and which of course constituted the 
sun itself ; and these little nebulse, throwing off, in 
their turn, successive lesser rings, which were to 
form the satellites of each, the whole of the 
detached portions, the earth among the rest, in the 
course of time — immeasurable time — condensed 
into globular form, that form which all bodies left 
free to take their own shape, naturally assume. 
One exception only to a globe occurs in the solar 
system, and that is the ring of Saturn, which 
Laplace considers to be an exception that proves 
the rule, inasmuch as it gives a strong confirmation 
of the probability of the original ringed condition 
of the various members of the system. The reason 
why this annulus is not found in other cases is that 
the mechanical conditions requisite for the perma- 
nent maintenance of a ring form would be very 
seldom fulfilled. Lest any one should be inclined 
to doubt the possibility of the solid earth and all 
