RS ee ie 
ern mate 
142 
the present volume, the first of a series of essays which he 
proposes to write for the instruction of his pupils and others 
in “ Forest-zoology,” z.¢., in Zoology with especial reference 
to the wants of those who are engaged in the care and pre- 
servation of forests. The present volume is devoted to 
the class of Mammals ; a second will relate to the Birds ; 
and a third to the Insects ; these being the three princi- 
pal divisions of the animal kingdom with which “ fores- 
ters” are mostly brought into contact. Zoology in the 
abstract, or “scientific zoology,” Dr. Altum observes, is 
the foundation upon which all knowledge of the various 
applications of zoology must be based, Dr, Altum there- 
fore adopts a strictly scientific arrangement for his work, 
commencing with a definition of the class of Mammals, and 
taking the various groups of this class in systematic 
order. The work being intended for those whose labours 
are to be in the forests of Central Europe, only European 
species are included. But the Quadrumana, Prosimia, 
and other orders restricted to foreign countries, are intro- 
duced in their proper places, and some general informa- 
tion concerning them, together with a short account of 
their leading divisions, is given. Special attention is paid 
to those species of Mammals which the forester is most 
likely to be brought into contact with, such as the squirrels, 
field-mice, beaver, deer, and others ; and full particulars 
are given of the modes in which forest trees are injured 
or attacked by them. 
_ Dr. Altum’s volume, thus composed, seems to be in 
every way well adapted for the purpose for which it is in- 
tended. Dr. Altum is fortunate in having, in Blasius’ 
well-known work on European Mammals, an excellent 
guide to the scientific history of other animals, which he 
wisely follows. An English writer on the same subject 
would not be so well off, for the only modern work on 
British Mammals is now long ago out of print, and there 
seems to be no prospect of a second edition of it being 
published. In this, as in nearly every other branch of 
science, we have constantly to go to Germany for assist- 
ance, 
LETTERS TO THE EDITOR 
[ Zhe Editor does not hold himself responsible for opinions expressed 
by his correspondents. No notice is taken of anonymous 
communications. | 
The Meteorology of the Future 
I CANNOT quite agree with Mr. Lockyer that the most important 
question in meteorology is the discovery of a cycle. Were it 
even so well proved, it would still be but an empirical law. In 
my opinion the chief desideratum of the science is a dynamical 
theory of barometric waves; and the data for this are to be 
found not merely in records of barometric fluctuations in one 
place, nor by comparing the records in several places at or near 
the sea level, but by comparing the records at places separated 
by the greatest possible vertical distance, though horizontally 
near each other. Such records do not yet exist, and they can be 
had only at specially chosen stations ; the summit and the base 
of Teneriffe, for instance, or of Etna. The latter would probably 
be the best, as it is in the variables. It is not at all certain that 
the fluctuations of the barometer at the summit and at the base 
of a high mountain would be nearly alike. It is stated by Kaenitz 
that while the barometer in the hottest part of the day falls 
at the sea level, it rises at a height of a few thousand feet. The 
reason why it rises at the higher station is that the entire column 
of air is lifted up by the expansion due to heat, and thus a larger 
proportion of the column comes to be above the station, This 
cause does not act at the sea-level, and the barometer there falls 
in consequence of the outflow of air from the top of the column, 
It is much to be desired that the attention of scientific men and 
scientific committees should be directed to this subject, as without 
such sets of comparative observations we shall never have all the 
data for a complete theory of barometric waves. 
Old Forge, Dunmurry JoserH JOHN MuRPHY 
Pe ey eee ean el 
NATURE 
 [Dec. 26, 1872 
Popular Science in 1872 
SCIENTIFIC information in a popular form is one of the demands 
of the age, and we find it supplied even in publications by no 
means exclusively devoted to Science. It would be a great loss, 
however, to the professed students of science, if they should 
remain unacquainted with the following remarkable contribu- 
tions to our knowledge of electricity, merely because they occur 
in the December number of Se/gravia,*in an article entitled 
“Ts Electricity Life?” dp 
adt 
“‘The ocean, for instance, is compounded of water and salt ; 
one is an electric, the other not. The friction of these causes 
the phosphorescent appearance so often observed at sea.” 
“*That all created living bodies are electric there can be no 
question ; and as little that some persons, animals, and plants, 
are more electric than others. Two forms of the latter are 
familiar. Few schoolboys are guiltless of experiments on poor 
puss, from whose much-enduring back electric sparks may be 
drawn, especially in dry frosty weather ; and most young ladies 
have admired the elegant sensitive plant, whose leaves seem to 
move and feel, 
“and with quick horror fly the neighbouring hand,” 
that draws from it the electricity which it contains more than 
other plants ; and its leaves at once fall flaccidly, until a new 
supply of electric force renders them once more turgid. 
“*But bodies have not only electricity within them, but an 
electric atmosphere, of the form of the body which it surrounds, 
and which is attracted by it. Without this we could not shake 
hands with a friend, or kiss a lip, without the danger of the 
excess of electricity flying off and destroying us, or the he or she 
that we would greet or kiss. Perhaps it is the commingling of 
these electric atmospheres that makes kissing so nice, 
‘*Two conditions of the human body are also illustrative of 
its varied electric action. A person who has the small-pox 
cannot be electrified, while sparks of electricity may be drawn 
from the body of a patient dying of choleta, In the first instance 
it appears that the body is fully charged with its own electriclty, 
since it is impossible to electrify a body beyond a certain degree ; 
in the latter there seems to be a tendency to pirt with the 
electric force which is essential to the support of life, and which 
may account for the distressing and rapid weakness of cholera- 
patients.” ; 
Upon the Direction in which the North Magnetic Pole 
has moved during the last two Centuries 
In an article upon Terrestrial Magnetism in the current 
number of the Zdinburgh Review, referring to the fact that the 
compass-needle does not now in England point due north and 
south, and that it changes its position slightly from year to year, 
but that from our present ignorance of the source and laws of 
this change we cannot say thatit will hereafter beas much in one 
direction as it has been in another, the writer remarks (p, 424): 
“Still the strictly Arogressive character of this change com- 
pels us to regard it as the expression of some determinate 
cause or causes. The question then arises, Where are 
these to be found? Now, from whatever point on the 
earth’s surface we contemplate the phenomenon, we find our- 
selves in the presence of two distinct magnetic systems. This 
was first clearly recognised by Halley as a necessary conse~ 
quence of even the scanty information at his command, and the 
accumulated observations of two hundred years haye corroborated 
in a very remarkable manner the conclusions at which he arrived 
—that of these two systems one was fixed and the other zz 
motion.” 
Itis a matter of some interest to ascertain in what directions 
the system in motion has gone in the interval mentioned. Sir 
Edward Sabine gives us some information on this point. In his 
paper upon Terrestrial Magnetism, in ‘‘Johnston’s Physical 
Atlas,” p. 72, he says : “ The change of longitude of the stronger _ 
pole, since Halley placed it on or about the middle of California, 
appears to have been small; but, on the other hand, the weaker 
pole, which is now found in Siberia, was placed by Halley near 
the meridian of the British Islands, and, adopting Halley’s mode 
of reasoning, the present disposition of the lines of declination 
corresponds to this change.” 
Of the northern poles of the two magnetic systems in Halley’s 
time, one appears to have been in the longitude of California, the 
