426 

A FEW minutes after sunset on Thursday last (23rd) I saw a 
very fine meteor in the direction E.N.E. t 
Its course at first appeared southerly, then, bending down- 
wards, it seemed slowly to drop in a direction perpendicular to 
the horizon, and I lost sight of it behind a clump of trees. Its 
light was exceedingly brilliant. J. F. DUTHIE 
Leyton, Essex, March 27 
Books Wanted 
THE only way in which your correspondent of last week, Mr. 
H. J. Watson, is likely to obtain the volume of the * Annales de 
Chimie,” containing the paper of Braconnot, (not Bracconot, the 
misprint is Sir John Herschel’s), and that of the “ Philosophical 
Transactions’ with Dr. Prout’s paper, would be to request some 
second-hand scientific bookseller to place them on his list of 
“<desiderata,” so that they may be brought under the notice of 
those who are likely to have duplicates. 
Perhaps Mr. Watson is not aware that there is a good abstract 
of Braconnot’s paper, occupying just over six pages in the 
Quarterly Journal of Science, vol. viii. 1820, and also short 
abstracts in the Edinburgh Philosophical Fournal, No. iv. 1820, 
and Tulloch’s Philosophical Magazine, vol. lv. 1820. It has 
also been reprinted into some foreign scientific periodicals, a list 
of which may be seen on reference to the ‘‘ Royal Society’s 
Catalogue of Scientific Papers,” vol. i. 
Oxford, March 24 Jas. B. BAILEY 
Measurement of Mass and Force 
PROFESSOR EVERETT, towards the close of his much-needed and 
exhaustive letter in NATURE (March 2) on the Measurement of 
Mass and Force, proposes to supply an undeniable want in Dy- 
namics by coining the word 4:77/ to denote that force which, act- 
ing on an avoirdupois pound of matter for a second, generates a 
velocity of a foot per second. He then adds, ‘‘ If we substitute 
gramme for pound and metre for foot, we obtain a different unit 
which must be called by a different name.” 
Now one, and perhaps the only, objection to this is that in the 
face of the rapidly spreading metrical system it seems injudicious 
and somewhat savouring of retrogression to appropriate the most 
suitable root at our disposal to designate a force-unit depending 
upon the Aownd and foot (the abandonment of which is now only 
a question of time), while that based on the gramme and metre 
is sent a begging. I would therefore suggest to Prof. Everett 
that a Aizit (or simply the monosyllabic 42) be defined as ¢ha¢ 
force which, acting on a gramme of matter for a second, generates 
a velocity of a metre per second ; and then there would follow as a 
matter of course Ailokim, &c., suggestively and conveniently de- 
noting either ‘‘the amount of force which, acting on a £i/ogramme, 
&c., of matter for a second, generates a velocity of a metre per 
second,” or, ‘‘the amount of force which, acting on a gramme of 
matter for a second, generates a velocity of a Av/ometre, &c., per 
second.” 
Besides Kinetics and Heat (see NATURE, vol. i. p. 606) there 
is another department of science where a similar want exists— 
less pressing, perhaps, as yet, but felt, nevertheless. This is 
Electricity. Taking as basis Sir W. Thomson’s general defini- 
tion of unit quantity of frictional electricity (Cams. and Dudl. 
Mathematical Fournal, March, 1848) a particular unit (ze. a 
unit dependent upon previously fixed particular units of force and 
distance) might be chosen, formally defined, and named. 
This question of units of measurement and their names appears 
to me to be anything but trivial. A science, which, by the 
choice of ove good system of units, and the adoption of a sugges- 
live definite and uniform nomenclature, has put its house in order 
for the proper reception of the powerful chief Mathematicus, has 
laid the foundations of true and rapid progress. 
College Hall, St. Andrews Tuomas MUIR 

The Earthquake 
A RATHER severe shock of earthquake was experienced in this 
neighbourhood on Friday, March 17. The day in question had 
been remarkably calm, and a heavy suffocating feeling in the 
atmosphere noticed. About 11.15 P.M. a somewhat loud rumbling 
noise was heard as if a heavy waggon was passing over pave- 
ment ; windows, chandeliers, furniture were violently shaken. 
Cups and saucers made themselves heard, and beds in some cases 
were distinctly felt to oscillate and heave like a ship at anchor. 
Breathing in some cases became difficult, but whether from fright 
or the oppressive state of the atrakepnets does not appear. The 
vibrations were apparently horizontal, and probably in a direction 
NATURE 



[March 30, 1871 
from N. to S., lasting about three or four seconds, Poultry and 
cage birds showed particular distress by the noise and fluttering 
which they made. The temperature, which on the previous 
Tuesday night had fallen as low as 17°, suddenly changed, and 
the minimum of Friday night was 41°. Saturday morning was 
remarkably warm ; the black bulb thermometer in vacuo reading 
92°. The barometer showed no unsteadiness, but had been 
gradually rising for some days previously. The shocks seems to 
have been felt from the south of Scotland as far as the north of 
Derbyshire, much the same account having been received from 
each locality. Tuomas FAwcetrT 
Blencowe, Penrith, March 20 
THE earthquake recorded for the night of Friday (17th) last 
was felt here about 11 P.M., distinct vibration being observed by 
two members of my household. 
In support of the theory that shocks are mainly noted along 
lines of fault, there is a considerable one within a short distance 
extending northwards for some miles. 
CuHaRLES HENRY MIDDLETON 
Lingen Vicarage, Presteigne, Herefordshire, March 23 

A SLIGHT shock of earthquake was felt and heard in this 
neighbourhood at about 9.55 on Monday night last, the 2oth 
instant. 
The duration of the shock was not longer than three seconds ; 
it was accompanied as if by a muffled explosion, followed by a 
slight rumbling of the earth, anda gradual dying away of the 
sound, which seemed to be in an easterly direction. The last 
sensation is obviously not very reliable, as much will depend upon 
the position in which the hearer was sitting. 
Henry Cooper Key 
Stretton Rectory, Hereford, March 23 
The Reality of Species 
AMONG the many misconceptions that have arisen in connection 
with the doctrines of evolution appears to be one that species 
have no real existence. In a recent review (appearing in one of 
the best London papers) of Mr. Mivart’s work, this mistake is 
strongly expressed, the writer appearing to entertain a profound 
contempt for anyone who still retains the foolish notion that there 
is any such thing as a species in nature. Every working natu- 
ralist knows well that most assuredly species do exist, and that 
in the most positive manner, not being conventional merely, but 
separated from one another in nature by distinct and real 
characters. 
Fortunately for the doctrine of natural selection, it does not 
in the least question this fact, for did it so, it would be disposed 
of at once by pointing to a red admiral and tortoiseshell butterfly 
flitting side by side. It cannot be too distinctly insisted on that 
natural selection opposes no barrier whatever to the reception of 
the idea of distinct and separate species. That which it has 
destroyed is the notion of the constancy of species if the idea of 
time be set on one side. To argue that species have at the pre- 
sent day no separate existence because they had formerly a 
common origin, is a foolish confusion. The separate existence 
of a full-grown and mature animal is not questioned, because at 
one period it was a bud closely connected with its parent. In 
point of fact the question of species is really very similar to that 
of individuality, viewed as a question of origin, the individual 
and the species are both untenable ideas ; but viewed at any one 
moment, both individual and species are among the most promi- 
nent and undoubted facts of our experience. Equally futile is it 
to argue that species have no existence, because we cannot 
exactly define what we mean by a species. It is well known 
that all the efforts of biologists have hitherto failed to produce a 
satisfactory definition of life. Are we, then, to conclude there is 
no such thing as a living animal ? 
The evolutionist contemplates throughout the universe a power 
underlying all things, indestructible and infinite, most various in 
its manifestations, always changing and always shifting, but 
steadily in a given direction, not revealed to man as a separate 
existence, but known only by its changes and movements, and 
veiled under the form of matter. Side by side with this universal 
and unknowable force he sees an opposing power, a tendency in 
things and matter to be always as they have been, a tendency 
which the restless force las ever to overcome ; but as soon as 
this has gained its victory, again is it subject to the grasp of its 
ignoble foe ; the struggle, though becoming ever more and more 
one of ‘detail, is no spasmodic one, though more reyealed to us 
