. Feb. 9, 1882] 
(abundance of suitable nourishment the primary condi- 
tion); theory of propagation ; animal ethics ; and lastly, 
human ethics. 
Abriss der Zoologie fiir Studirende, Arste und Lehrer. 
Von Dr. A. Brass. (Leipzig: W. Engelmann, 1882.) 
IN this octavo volume of over 360 pages we have a sketch 
of the modern aspect of zoology fairly well executed, and 
with woodcut illustrations after Frey, Heckel, Kolliker, 
and Gegenbaur. The first section treats of zoology in 
general, discusses the subject of the differences between 
the animal and vegetable kingdoms, and considers the 
animal in general. The second section is devoted to the 
morphology and developmental history of animals. The 
third is the systematic portion. The classification adopted 
is for the most part a copy of Claus’s. The volume 
forms a handy compendium of zoological science, and, 
like all the works from the establishment of the well- 
known Leipzig publisher, is well printed on good paper. 
The Two Hemispheres: A Popular Account of the 
Countries and Peoples of the World, By G. G. Chis- 
holm, M.A. Illustrations. (London : Blackie and Son, 
1882.) 
THIS work contains in one volume much useful geogra- 
phical information, methodically arranged. It is, indeed, 
a systematic and succinct account of the various con- 
tinents, countries, and oceans, somewhat after the style 
of a gazetteer, for which it may be used by means of the 
copious index. The information seems to us in the main 
accurate, though many of the illustrations appear well worn. 
Mr. Chisholm, however, gives the old erroneous measure- 
ments of Mounts St. Elias and Fairweather, in Alaska, 
evidently unaware of the survey made by Dall six years 
azo, and which showed them to be 4000 feet higher than 
given here. 
LETTERS TO THE EDITOR 
[The Editor does not hold himself responsible for opinions expressed 
by his correspondents. Neither can he undertake to return, 
or to correspond with the writers of, rejected manuscripts. 
No notice is taken of anonymous communications. 
[The Editor urgently requests correspondents to keep their letters 
as short as possible. The pressure on his space is so great 
that it ts impossible otherwise to ensure the appearance even 
of communications containing interesting and ncvei facts.] 
Sun-spots 
THE spot seen on the sun by Mr. W. A. Holland (NatuRE, vol. 
XxV. p. 316) would appear to have been simply a large sun-spot 
which made its appearance at the sun’s east limb on November 
15, and went off the disk on November 27. It is shown on 
photographs taken at Greenwich on November 16, 17, 18, 19, 
2Q, 21, 23, 26, and 27. On November 21, 11h. a.m. it was 
north-east of the centre, Pos-angle 50° 27’, Dist. 0°188 of sun’s 
radius, and on November 23 of. it was north-west of 
the centre Pos-angle 313° 39’ dist. 0412. The estimate 
of its size by Mr. Holland is very much exaggerated, the 
dimensions of the whole spot (nucleus and penumbra), as mea- 
sured on the photographs, being one-twentieth of the sun’s dia- 
meter in length, and one-twenty-fifth in breadth. The area, 
corrected for foreshortening and expressed in millionths of the 
sun’s visible hemisphere, was $32 for the whole spot, and 152 
for the nucleus on November 21, and 970 for the whole spot, 
and 171 for the nucleus on November 23. The spot had begun 
to break up between November 21 and 23, and the area for 
November 21 is really the largest as applying to a single un- 
divided spot. This spot is one of the largest yet recorded at 
Greenwich. Two other large spots of about the same size were 
photographed in 1881, on March 22 and June 1, their areas 
being respectively 919 for the whole spot, and 195 for the 
nucleus ; and 931 for the whole spot, and 158 for the nucleus. 
The next largest spot in previous years was that of 1877 
November, with an area of 8o1 for the whole spot, and 109 for 
the nucleus, 
While on the subject of sun-spots, I may mention with refer- 
NATURE 
337 
ence to Mr. J. B. N. Hennessey’s letters on an Outburst of Sun 
Spots (NATURE, vol. xxiv. p. 508, and vol. xxy. p. 241) that a 
photograph taken at Greenwich, 1881, July, 244 23h. 11m, 10s., 
G.M.T., only 11m. before the new group was noticed on the 
ground-glass at Dehra Doon, shows no indication whatever of 
the group in question, and that no trace of it appears on a photo- 
graph taken next morning, July 25, 22h. 17m. 55s. G,M.T. 
Thus the new group, if real, must have formed suddenly in less 
than eleven minutes at a part of the sun’s surface where there 
was not the slightest previous disturbance of the photosphere, 
and must have completely disappeared within the space of 23h. 
It might have been expected that the granules of the photosphere, 
which are well defined in the Greenwich photographs referred 
to, would have given some indication of such an outburst. 
W. H. M. CHRISTIE 
Royal Observatory, Greenwich, February 6 
THE importance attached to the solar observations of Mr. 
W. A. Holland by so great an authority as Sir W. Thomson, 
would alone suffice to warrant me in forwarding for your publi- 
cation exact drawings of the spots observed on November 22 
and 23 of last year, and the wording of the letters of Mr. Holland 
makes it still more urgent to determine the precise extent of the 
spots in question. 
The small optical power used on November 22 and 23, on 
board the Savah Bell, places the result almost on a level with 
direct eye observations, and the description strongly recalls.to 
mind the accounts gfven of solar spots previous to the discovery 
of the telescope. Thus on November 22 we have two eye-esti- 
mates of the size of the spot. ‘‘I, myself,” writes Mr. H., 
“estimated the spot on the sun to be 4 diam,, but conferring 
with the captain, he estimated it to he + diam, ; it was purely 
an estimate of the eye.” 
The pictures of the sun, which I inclose, were taken at Stony- 
hurst Observatory on November 20 and 22, and they give an 
exact outline of the spot seen on board the Sarah Bell, clearly 
showing what meaning we may reasonably attach to those 
ancient carefully denoted sun-spots, which were said to have a 
diameter equal to 4, 4+, or even 4 of the solar disk. The length 
of the spot observed on November 22 agrees very fairly with 
Mr. H.’s approximate estimate, if we include the whole group, 
but this gives a very incorrect notion of the spot-area, and of 
the disturbing forces then apparently at work in the sun. 
From accurate measurements of the original drawings, which 
give the relative dimensions of the spots on the solar disk, I find 
the diameter of the sun to be 267 mm., the length of the group 
54mm., andits breadth 22 mm., whilst the length of the large 
spot, including its whole penumbra, is only 15 mm. The group is 
a scattered one, and the whole spot area in the picture can 
scarcely exceed 225 sq. mm., and therefore, being situated almost 
at the centre of the disk, will not cover more than one thousandth 
part of the visible hemispheres, although the whole group is 
spread over a space nearly five times as large. We thus get a 
more correct notion of the disturbance on the solar surface than 
by measuring merely the diameter of the group, or by expressing 
the spot area in millions of square miles. 
The drawing of November 22 contains another spo‘ in the 
w.p. quadrant, which is not mentioned by Mr. Holland, but 
which a few days previously, when nearer the centre of the disk, 
was as conspicuous an object as the spot under discussion, and 
was easily seen by the naked eye on November 18, shortly after 
sunrise. The group which followed was then near the limb, 
and was a fine object ina small binocular, but not visible to the 
naked eye, 
The fact of two separate spots, each seen easily without a 
telescope, being on different portions of the solar disk at the 
same time is, I think, rather extraordinary, but the area covered 
by spois has never approached of late to what was sketched by 
Tacchini in 1871, or even what was photographed by Rutherfurd 
in 1870. I might perhaps also mention that the spot which 
crossed the disk in May and June was as large as that of 
November, S.. J. PERRY 
Stonyhurst Observatory, Whalley, February 5 
[The drawings sent by Mr. Perry seem to us to quite bear out 
his statements. —ED. | 
Rime Cloud observed in a Balloon 
A SINGULAR phenomenon was observed in Paris in the month 
of January. An obscure cloud remained ina state of suspen- 
