May 29, 1902 | 
NATURE 
1Ol 
peratures and the formation and decomposition of double 
salts. Although the present volume is a second edition 
of the work, yet the text is not free from misstatements. 
On p. 87 we are told that ‘when liquids mix in all pro- 
portions .. . then it is possible to make a complete 
separation of the constituents by a fractional distillation, 
provided the vapour pressures of the two differ,” a state- 
ment which is afterwards contradicted by examples which 
are given of the different types of liquid mixtures. On 
p. 210 we are told that the ferrous ion is greenish-black 
in colour, and on p. 260 that all binary organic acids 
satisfy the dilution law of Ostwald. Misprints are also 
not uncommon and authors’ names are not always cor- 
rectly spelt, ‘‘ Tammen” for ““Tammann” and ‘ Pebel” 
for “ Pebal” being instances. 
If, however, the defects here alluded to are remedied 
in the next edition, the book will, without doubt, serve as 
a very useful aid to students of physical chemistry. 
H. M. D. 
Practical Botany for Beginners. By ¥. O. Bower, Sc.D., 
F.R.S.,and Dr. T. Gwynne-Vaughan, M.A. Pp. xi + 
307. (London: Macmillan and Co., Ltd., 1902.) 
Price 3s. 6d. 
THIS excellent little book, written by Prof. Bower in 
1894, appears in a second edition after being subjected 
to careful revision. Mr. Gwynne-Vaughan now shares 
with Prof. Bower the author’s responsibility. The more 
prominent changes are the adoption of the nomenclature 
introduced with the stelar conception and a more elabo- 
rate description of grosser morphological features. The 
number of seeds described is increased to eight Dicoty- 
ledons and three Monocotyledons, and more than twenty 
flowers are taken as types of these two groups. The 
main types remain the same, except that the elm gives 
place to the lime. Other additions are the stems of 
Ricinus, Veronica Beccabunga (aquatic Dicotyledon), 
Elodea Canadensis (aquatic Monocotyledon), and leaves 
of Ligustrum, Hedera, Deschampsia and Phormium. 
The paragraphs on reserve and transitory materials 
have been considerably added to and improved, so that 
suitable material and the necessary tests are given for 
demonstrating the presence of starch, proteids and 
various sugars in the vegetative parts and in seeds. 
Exception may be taken to certain types chosen—for 
instance, Marchantia and Fucus—but obviously the 
general occurrence of these has weighed with the authors 
in their choice. Passing to methods of manipulation, 
glycerine and chlor-zinc iodine are almost exclusively 
recommended as mounting media; in several cases, 
notably Pinus, double staining and mounting in Canada 
balsam would give better results, while mounting in 
water avoids undue swelling of the walls of phloem 
cells such as follows the use of glycerine and Schulze’s 
solution. 
The book is already so well known that it is unneces- 
sary to emphasise the carelul arrangement of subject and 
the clear descriptions which characterise it. 
Quelgues réflexions sur la mécanique suivies dune 
premiére lecon de Dynamique. Par Emile Picard, 
Mem. Inst. France. Pp. 56. (Paris: Gauthier Villars, 
1902.) 
THE first part is based on a report drawn up by M. 
Picard in connection with the Paris Exhibition of 1900 
dealing with modern views on the principles of mechanics 
and in particular on the “energetic” method, and the 
dynamical system of Hertz. The second part consists of 
the first lecture given by M. Picard, since 1894, in his 
course on general mechanics, introducing the elementary 
principles of dynamics. It differs somewhat from the 
conventional treatment, and in this country Newton’s 
third law will probably be regarded as constituting a 
less artificial definition of ass than is used by M. Picard. 
NO. 1700, VOL. 66] 
ETERS, LO Hite, E DIOR 
\The Editor does not hold himself responsible for opinions ex- 
pressed by his correspondents. Neither can he undertake 
to return, or to correspond with the writers of, rejec.ed 
manuscripts intended for this or any other part of NATURE, 
No notice ts taken of anonymous communications. | 
Volcanic Eruption in Java, Brilliant Sunset Glows 
in 1901, and probable Glows from the Eruption in 
Martinique. 
THE brilliant sky glows and sunsets following the eruption of 
Krakatoa, near Java, on August 26 and 27, 1883, threw a flood 
of light on thé movements of the upper atmosphere in a way 
which was probably not otherwise possible. Up to that time it 
had been supposed generally by meteorologists that the air form- 
ing the trade winds ascended at the equator and turning toward 
the poles became a south-westerly current in the northern hemi- 
sphere and a north-westerly current in the southern hemisphere 
flowing over the trades. After the explosion eruption of 
Krakatoa, the large mass of observations gathered by the com- 
mittee of the Royal Society and the admirable discussion of the 
optical phenomena by Russell and Archibald (‘*‘ The Eruption of 
Krakatoa and Subsequent Phenomena,” London, 1888) brought 
out the following facts :— 
(1) The haze, sky glows and brilliant sunsets progressed from 
east to west three times around the world within the tropics at a 
rate of about seventy-five miles an hour. ; 
(2) They spread northward and southward from 20° N. and 
20° S. very slowly, taking from September 2 to about October 7 
for the conspicuous phenomena to spread from 20° N. to 
35° N. in America, a velocity of about one-half a degree a day, 
or one mile an hour. 
(3) Above 35° latitude the progressive motion was rapid and 
apparently from the south-west in the northern hemisphere and 
from the north-west in the southern hemisphere. 
There are two other important conclusions which I think may 
be drawn from the data, and these are :— 
(1) The atmosphere between 20° N. and 20° S. moved with a 
nearly uniform velocity from the east ; otherwise it would have 
been impossible to trace the movement of the dust cloud around 
the world three times, because a very slight difference in velocity 
or direction at different latitudes would very soon have destroyed 
the individuality of the cloud, whereas Russell’s lines of first 
appearance are nearly parallel with each other between 20° N. 
and 20° S. 
(2) There are frequent temporary disturbances in this region 
by which the air is carried rapidly outward in narrow belts into 
extratropical regions. One of these disturbances was shown 
on August 27, when the dust was carried rapidly to Japan, 
another on August 28, when dust was carried to South Africa, 
and another on September 1, when dust was carried to 
Santiago, Chili. 
The movement of the atmosphere above the tropics estab- 
lished by this investigation differed so from that supposed to 
exist by meteorologists that it was sought to explain it as a 
temporary movement and not representative of average con- 
ditions. But Abercromby was so much impressed by the 
phenomena that he began to gather observations of the move- 
ments of cirrus within the tropics. These are published in the 
volumes of NATURE between 1887 and 1890. Hildebrandsson 
has pursued the subject farther, and his results show that in the 
equatorial regions between 20° N. and 20° S. the prevailing 
movement of the cirrus is from the east. North and south of 
these latitudes the directions change to a movement from the 
west. It is probable that between these two opposing belts of 
wind there is a nearly calm zone across which the air movesf 
very slowly from the equator. 
These facts are dwelt on in order to show the importance of 
such observations preliminary to calling attention to recent sky 
glows and volcanic eruptions. 
In the autumn of rgor, Mr. Rotch, Mr. Sweetland and myself 
noticed independently that the sunsets were more brilliant than 
usual at Blue Hill (lat. 42” 13’ N., long. 71° 7’ W.), and the 
following notes were entered in the records of the Observatory :— 
“October 7.—Since about September 20 the sunsets on clear 
days, including to-day, have shown unusually bright colours, a 
bright red predominating and lasting near the horizon for three- 
quarters of an hour or longer; November 2, a very brilliant sun- 
set, red prevailing, and the colours continued for about forty-five 
