— 
Fune 29, 1871] 
NATURE 
163 

cavities of fossil crinoids to be filled with a siliceous sub- 
stance perfectly injecting their most delicate cellular struc- 
ture, and which Dr. Hunt, on chemical analysis, found to 
be a hydrous silicate allied to jollyte. I have since, in 
examining with the microscope various specimens of lime- 
stone in the collection of McGill College, met with a 
British example of this kind of injection, to which I would 
wish to direct the attention of your microscopists. It isa 
specimen of olivaceous, imperfectly crystalline limestone, 
labelled Llangedoc, Wales. The only distinct fossil which 
it contains is a small body having the characters of the 
genus Verziczllopora. It is filled, however, with crinoidal 
fragments and fragments of shells, and, when sliced, dis- 
plays a few very minute univalves, probably of the genus 
Murchisonia, and also portions of a sponge-like organism 
with square meshes. The pores and cavities of many of 
these fossils are filled with a greenish or brownish finely 
crystalline silicate, which must have been introduced when 
the organic bodies were still recent, and which Dr. Hunt 
has ascertained to have the following composition :— 

Silica : . 35°32 
Alumina . G f H c 22 66 
Protoxideof Iron . és f 21°42 
Magnesia . 5 > 6°98 
Potash. 5 1°49 
Soda 5 5 5 eX ey/ 
Water . ° . . 11°46 
100'00 
So that this mineral is almost identical with jollyte. The 
fact that it fills the minute pores and cavities of the fossils 
can be seen in transparent slices, especially under pola- 
rised light, and also in decalcified specimens. The filling 
is not, however, so perfect as in the New Brunswick 
specimens above alluded to. The best, which I suppose 
to be Upper Silurian, is worthy of the attention of those 
who may have access to it, as presenting an interesting 
example of Silurian fossils preserved in the same way with 
the Laurentian Eozéon. It affords another palzozoic 
illustration of a mode of preservation of the structures of 
fossils, which, though perhaps more prevalent in the Lau- 
rentian and Cretaceous than in any intervening periods, 
is to be met with here and there throughout the geological 
series, and is of equal interest to the palaontologist and 
the chemical geologist. J. W. DAWSON 
Montreal, June 8 

NEW THEORY OF SUN-SPOTS 
LATE number (1,835) of the Astronomische Nachrich- 
ven reproduces from the notices of the Royal Saxon 
Scientific Society a paper on the above subject by Pro- 
fessor Zéllner. The author believes that he is the first 
who has attempted to account for the periodicity of the 
spots by agencies confined to the sun itself, while he re- 
jects the notion of planetary influence to which the phe- 
nomenon has been commonly attributed. In this, how- 
ever, he is not quite correct, for in the April numbers of 
Cosmos last year there appeared a transcript of a paper 
read before the Belgian Academy of Sciences, by M. 
Bernaerts, who tries to explain the various phenomena of 
the sun spots without reference to any extra-solar action. 
Prof. Zéllner, like M. Bernaerts, accepts the theory of 
aliquid forming the surface of the sun; but while the 
Belgian savant considers the spots as perforations in the 
licuid layer traversed by downpouring currents of gases 
that had previously risen through the liquid from the 
gaseous nucleus, Prof. Zéllner believes the spots to be 
formations of slag or scoriz caused by a certain local 
cooing of the liquid surface. Over this glowing liquid 
is aglowing atmosphere, which contains, in a vaporous 
state, a portion of the matter belonging to the liquid. 
‘The same as on the earth, if this atmosphere is cloudless 


| oes : 
and calm, radiation and cold are induced ; and where 
this occurs the slag-like products are formed, and spots 
become visible. But vaporous condensation is also a 
consequence of the cold. Clouds, therefore, are de- 
veloped, the radiation is checked, the liquid surface re- 
gains its former heat, and the spots are dissolved and dis- 
appear ; so that the very cause that effects their forma- 
tion also tends to their dissolution. ‘The repetition of the 
same operations gives the spots the character of “ inter- 
mittent phenomena ;” but their occurrence, as wellas their 
duration, depends on such a complication of meteoro- 
logical processes that those phenomena cannot be con- 
sidered otherwise than as perfectly casual. 
The action of a spot on the atmosphere in cooling it, 
and causing cloudlike condensations that oppose radia- 
tion and restore the heat, makes the presence of a great 
spot unfavourable to the formation of other spots, and 
Prof. Zollner arrives at the conclusion that “a sun-spot 
exerts within a certain area, and according to its size, an 
influence that prevents or obstructs the formation of other 
sun-spots.” Thus, it appears, he explains the zsolation of 
the spots. But they occur also in groups over a wide 
extent of surface, and he infers that “the same conditions 
of the solar atmosphere that induce the formation of a 
spot in any one place, prevail in general over a larger 
space than that occupied by the spot, so that within the 
area influenced by those favourable conditions, the simul- 
taneous production of other spots is more likely than 
elsewhere.” The size of the spots depends plainly not 
on the amount of radiation alone, for the slag like pro- 
ducts have cohesive properties like our ice-flakes. 
I candidly admit that all this is by no means so very 
plain to me after reading the theory of the isolation of the 
spots; and I would refer the reader to the original for 
a better understanding of the two theories relating 
to the isolation and the grouping, than I have been able 
to attain to. I would al.o refer to the original for tke 
Professor’s views of the oscillations of solar temperature 
and the periodicity of the spots, which he discusses in 
several paragraphs. 
The appearance of the spots in certain zones on both 
sides of the equator he explains as the effect of currents 
in the liquid stratum. He asks us to imagine, in the 
first place, a motionless, atmosphere-enveloped globe 
maintained at a constant high temperature ; and, after 
explaining the results, he tells us to fancy: such a globe 
with a liquid envelope heated at bottom by contact with 
the surface beneath it, and cooled above by radiation. 
The lower parts of the liquid have a tendency to rise on 
account of their lower specific gravity, but their ascent 
anywhere is impossible unless somewhere else a sinking 
takes place. With equal conditions everywhere prevail ng, 
no motion in either direction could occur; but those 
equal conditions do not exist on the sun, whose axial rota- 
tion diminishes the force of gravity at the equator, This 
therefore favours an ascent of the heated lower portions of 
the liquid at the equator, and a sinking of the cooler 
upper parts in the regions of the poles. Two streams 
are thus induced ; one below flowing toward the equator, 
and one above in a contrary direction. The former as it 
progresses gains in temperature by contact with the hot 
surface of the globe ; while the latter in its sub-aerial route 
loses heat by radiation. Thus the polar regions of the 
sun are made cooler than the equatorial, as has, in fact, 
been shown by Secchi’s investigations. 
These movements in the enveloping liquid ( //i/ssigen 
Umhillungen) are the cause of atmospheric disturbances, 
producing in certain places a lowering of tempera- 
ture and condensation. The fall in temperature 
is favoured in two ways—by the mixing of the equa- 
torial and polar streams in high latitudes, and by the 
ascent of an air-current at the equator. As this air- 
current cools in rising its vaporous constituents are partly 
condensed in the form of clouds. Yet these clouds need 
not at all be of so low a temperature as to appear to us 
