602 
NATLTORE 
[April 20 1882 | 
namely, that their degree of disintegration would continue the 
sane. There could be no more chemical combination in the 
sun, if thus retaining all its heat, than in the rare matter of space. 
For chemical condensation to take place the heat contents must 
be reduced. An equal degree of absolute heat signifes an equal 
motive vigour of particles, and it is this motive vigour which 
enables them to resist chemical attraction. It may be supposed, 
however, that in dense matter the chemical attraction would be 
more effective from its increased energy through contiguity. Yet 
this is an erroneous idea; there is no real greater contiguity 
between the particles of dense than of rare matter. In both 
cases, the particles are brought incessantly into absolute contact 
through their vibrations. ‘The number of contacts of dense as 
compared with rare matter may be millions to one, but that can 
have no effect upon the result. If the chemical vigour be stronger 
than the vibratory vigour it will overcome it in the contact ; if it 
be weaker it will fail to overcome it, and a more frequent repe- 
tition of contacts cannot materially aid this re-ult. 
Thus all substances of equal absolute heat must be equal in 
degree of chemical integration, whatever their degrees of tensity 
or condensation. But the assumed equality of absolute heat 
cannot continue between dense and rare gases. The sensible 
heat of the dense gas tends to radiate out into the chilled rare 
gas. A constant and vigorous effort to equalise temperatures 
takes place. With every outflow of radiant heat from a sphere 
into space the absolute heat of the particles of the sphere de- 
crea e-, that of the rare matter of space increa-es. The 
absolute heat contents grow more unequal with every step to- 
wards equalisation of temperatures. Consequently a variation 
in chemical condition arises. The loss of heat by the sun, for 
instance, reduces the vibratory resistance to attraction, and with 
every such loss chemical molecules of greater complexity are 
formed. This heat is radiated into space. Probably some 
portion of this radiant heat is arrested and becomes local heat 
in the matter of space. If so the heat vigour of this matter 
increases, disintegration must ensue, and the increasing chemical 
condensation in the sun must be matched by an “increasing 
chemical disintegration in outer matter. 
During the myriad years of solar condensation, this process of 
heat-outflow has been continuous, so that now, despite its great 
excess of temperature, the absolute heat of solar matter must 
be far below that of an equal mass of the matter of outer space. 
Can the heat thus lost by the sun be recovered? If it could, 
the solar heat emissions might continue indefinitely. Dr. 
Siemens’ hypothesis offers a method of recovery, If the matter 
of outer space is drawn into the solar atmosphere by sucha polar 
inflow as he supposes, and subjected to the vigorous condensing 
influence of solar gravity, its volume must be very greatly de- 
creased, and much of its latent heat become sensible. And as 
its absolute heat-contents are far in excess of those of solar 
mutter, the result of such condensation must be a high degree 
of temperature, and a continual replacement of the radiated 
heat of the sun. Without any chemical integration taking place 
in this inflowing matter, the solar temperature may be kept up 
by its mere condensation, and by rendering available its great 
exce-s of absolute heat. With chemical integration, and the 
consequent much greater condensation, of course the heat- 
yielding effect must “be much more considerable. 
This inflow of outer matter to the sun is, in Dr. Siemens’ 
hypothesis, rendered possible by a continuous outflow of solar 
matter to outer space, thus eamyiae substance of low heat 
energy to be mingled with the rarefied exterior matter, whose 
high heat energy is thereby somewhat reduced. Such a process, 
however, has in it something of the flavour of perpetual motion. 
The sun is giving and taking, and its receptions may be equal to 
its emissions. It would thus constitute a machine yielding power 
to, and regaining power—to be again yielded—from the same 
substance. Yet there is another element in the case, which re- 
lieves it of this suspicious perpetual motion flavour. If the sun is 
constantly flinging off rare matter at a tangent from its upper 
atmosphere, there must be a reaction upon the rotatory energy 
of the solar sphere. It must be gradually losing its energy ‘of 
rotation, with extreme slowness, of course, since the weight 
thrown off is very slight, but in time the effect cannot but 
become a marked one, and perhaps this loss of solar energy 
may be the ultimate source of the new heat obtained by such a 
process. We may conceive of a like process taking place, to a 
less marked extent, in the large and rapidly rotating planets, 
such as Jupiter. CHARLES Morris 
Philadelphia, U.S 
UNDER this title Dr. C. W. Siemens, on March 2, presented — 
to the Royal Society a paper, which is published in NATURE, 
vol. xxv. p. 440. Therein, after noticing the hypotheses pro- — 
posed by Meyer, Helmholtz, and Sir William Thomson, to 
explain the maintenance of solar heat, he endeavours to show 
how the evergy apparently lost by radiation from the sun into 
space, may be gathered up and restored to the centre of our 
system. This he conceives to be effected through the interven- 
tion of attenuated matter diffused throughout space, which is 
the recipient of the radiated energy, and is continuously absorbed 
and again reflected by the centrifugal action of the sun itself. 
The matter diffused through space he supposes to include oxygen 
and nitrogen, hydrogen, aqueous vapour, and carbon compounds. 
besides solid materials which are probably exhalations from the 
sun, and constitute the so-called cosmic dust. 
In supp ort of this view of an interstellary nature Dr. Siemens 
cites Grove and Mattieu Williams, among others, but does not 
seem aware that its agency in gathering up and restoring to the 
sun its lost radiant energy, has been maintained by these writers. 
Sir William Grove, in his address as President of the British 
Association in 1866, attempted to find in this interstellar matter 
(whose nature and relations to our atmosphere he had already 
considered in 1843, in his celebrated essay on ‘‘ The Correlation 
of Forces”), a source of solar heat, inasmuch as the sun ‘‘ may 
condense gaseous matters as it travels in space, and so heat may 
be produced.” This same view suggests the title of ‘‘ The Fuel 
of the Sun,” by Mattieu Williams, a book published in 1860, 
the argument of which, as briefly resumed by me in an essay on 
«<The Chemical and Geological Relations of the Atmosphere,” 
in the American Fournal of Science for May, 1880, is as 
follows :— 
“The solar heat, according to Williams, is maintained by the 
sun’s condensation of the attenuated matter everywhere encoun- 
tered by that body in its motion through interstellar space. The 
irregular movements impressed upon the sun by the varying 
attractions of the planets, stirring up and intermingling the 
different strata of the solar atmosphere, and producing the great 
perturbations therein, of which the telescope affords evidence, 
are, in his hypothesis, the efficient agents inthe process. The dif- 
fused matter or ether, which is the recipient of the heat-radia- 
tions of the universe, is therebytdrawn into the depths of the solar 
mass ; repelling thence the previously condensed and thermally- 
exhausted ether, it becomes compressed and gives up its heat, 
to be, in turn, itself driven out in a rarefied and cooled state, 
and to absorb a fresh supply of heat, which he supposes to be, 
in this way, taken up by the ether, and again concentrated and 
redistributed by the suns of the universe.” 
The astronomer must judge between the different views of 
the mechanism of what may be called the process of solar 
respiration in this hypothesis, as put forward by Siemens and 
Williams respectively. We may call attention in this connection 
to Newton’s ‘‘ Principia,” book iii., proposition 12. 
The views of Grove and of Williams, cited in my paper of 
1880, are farther considered in an essay on ‘‘ Celestial Chemistry 
from the time of Newton,” read by me in November, 1881, * 
before the Philosophical Society of Cambridge, and reprinted 
from its Proceedings both inthe Chemical News and the American 
Fournal of Science for February, 1882. A perusal of this paper, _ 
to which Dr. Siemens alludes, will show that Sir Isaac Newton 
209 years ago conceived the existence of an interstellar ether 
made up in part from emanations and exhalations from the atmo- 
spheres of the earth, the planets, and the sun, and from comets. 
He further conjectured this interstellary medium to contain ‘‘ the 
material principle of life” and ‘‘the food of sun and planets,” 
furnishing ‘‘ the solary fuel,” and being copiously absorbed by 
the sun ‘to conserve his shining.” The relations of this inter- 
stellary matter to terrestrial life I have endeavoured to set forth 
in the paper just noticed. In connection with Sir William 
Thomson’s calculation of the density of the luminiferous medium 
therein mentioned, the reader is referred to a recent examination 
of the subject by P. Glan, in the Ammalen der Physik und 
Chemie, No. viii. 1879, in which he concludes that the lower 
limit of density would be more than 7000 times greater than that 
calculated by Thomson. 
* In a paper on the subject of an interstellar medium, read by me before 
the French Academy of Sciences (Comptes Rendus, September 23, 1878, 
page 453), I spoke of it as affording, in accordance with the ideas of Newton 
and of Grove, a means of material communication between celestial bodies 
and added: *‘ Cette théorie d’une échange universelle me paraissait fournir 
une explication de l’origine des poussiéres cosmijues.”’ 
