4 
NATURE 
[ NovEMBER 5, 1896 
endeavours to describe its past and predict its future 
experience in the briefest possible terms. It is this 
creation of Maturgese/sze by the mind, this invention of 
brief formulae, which is at once the glory and limitation 
of science. 
world of Dinge an sich, which we term nature, may be in 
and for itself; it seeks with all its ingenuity to describe 
bildlich symbolisch, what falls within the limits of its ex- 
perience. ‘The progress of science lies in the increasing 
comprehensiveness and brevity of its descriptions. 
Prof. Volkmann tells us that : 
“So lange die Naturwissenschaften mit einem inneren 
Verhaltnis zwischen Geist und Natur arbeiteten, war ihr 
Fortschritt gehemmt ” (p. 123). 
If this were true, then must natural science and the 
discovery, or rather zven/zon of natural law be for ever 
retarded, for science must always work at this very relation 
between mind and nature. It is, however, not the right 
but the wrong appreciation of the relation of mind to 
nature which checks scientific progress. The completion 
of the revolution we have hinted at in this review, so far 
from being detrimental to natural science, will go a long 
way towards freeing its workers from the attacks which 
have been made upon science from more than one 
quarter, and which have largely arisen from a confusion 
of the idea of mechanism with some form of materialistic 
theory. Released from the need of replying to external 
criticism and attack, science will have the more energy 
and leisure to progress quietly in its own proper field. 
KARL PEARSON, 
OUR BOOK SHELF. 
Text-Book of Comparative Anatomy. By Dr. Arnold 
Lang. Translated into English by Henry M. and 
Matilda Bernard. Part ii. (London: Macmillan and 
Co., Ltd., 1896.) 
THIS volume of Dr. Lang’s text-book treats of the 
Mollusca, Echinodermata, and Enteropneusta. To the 
first group of animals 283 pages are devoted, and to the 
latter two 319. The complete and systematic manner in 
which the structure and relations of the different families 
and orders described in this work are dealt with, renders 
each of the three chapters, into which the book is divided, 
a valuable monograph. Regarding the phylogeny of the 
Enteropneusta, Dr. Lang states that they “ are not closely 
related to any single large division of the animal 
kingdom” ; his treatment of them in this volume is suf- 
ficient evidence that he is not inclined to attach much 
weight to their supposed affinities with the Chordata. 
In a short notice it is quite impossible to give any idea 
of the interesting way in which the book is written. 
The English translation is all that could be desired ; 
the illustrations are excellent. The arrangement of the 
subject-matter has been carefully thought out, and refer- 
ence to any subject is assisted by the use of different 
kinds of type in the text. A long classified list of the 
important literature is givenat the end of each chapter. 
Experience: a Chapter of Prolegomena. By the Rev. 
Wilfrid Richmond. Pp. iv + 64. (London: Swan 
Sonnenschein and Co., Ltd., 1896.) 
ACCORDING to the author, the initial obstacle to the 
progress of philosophy is the doctrine that experience 
cannot give the knowledge of reality—that nothing can be 
definitely known. This view he demolishes by showing 
that reality is actually to be found within the field of 
experience, whence the sensible conclusion is arrived at 
that “ experience is the beginning and end of philosophy.” 
NO. I410, VOL. 55] 
The mind does not explain for us what the ! 
LETTERS TO THE EDITOR. 
(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, rejected 
manuscripts intended for this or any other part of NATURE. 
No notice ts taken of anonymous communications. | 
Islandic Earthquake Recorded at Paris. 
Le No. de NATURE du 15 octobre contient une note trés 
intéressante de Dr. J. Stefansson, sur le tremblement de terre 
survenu en Islande le 26 aout dernier. 
J’ai l'honneur de vous informer que les courbes relevées, & 
cette date, au magnétographe de l’Observatoire du Pare Saint- 
Maur, portent nettement la trace de trois troubles particuliers, 
paraissant se rattacher 4 ce phénomeéne. Le premier s'est pro- 
duit & 11h. 36m., et les deux autres, qui sont plus accentués, 
respectivement 4 11h. 42m. et 1th, 46m, du soir, temps moyen 
de Paris. Tu. MoureEAvux. 
Observatoire du Pare Saint-Maur, le 29 octobre. 
Earth Tremors at Edinburgh between August 25 and 
September 6. 
IN connection with Dr. J. Stefansson’s article in NATURE 
of October 15, on the ‘‘ Recent Earthquakes in Iceland,” it may 
be of some interest to note that the photo-recording bifilar 
pendulum, presented to this Observatory by M. d’Abbadie, and 
placed under my care by Prof. Copeland, exhibits on the dates 
given by Dr. Stefansson several strongly marked irregularities 
in the curve, which may possibly have had their origin in the 
Icelandic disturbances. The following table contains a list of 
all the pendulum oscillations recorded on the photographs 
between August 25 and September 6, with the Greenwich 
Mean Times of their occurrence. 
Edinburgh pendulum 
Earth- | oscillations. | Tilt of 
quakes in = | pendulum 
Iceland. | frame. 
Begin. End. 
| | ‘ 4” a, oa 
Aug. 25 9-25 a.m. | : o4 Slight. 
3 4.45 p-M.| 5.50 p.m. | o6 =| Slight. 
26 |g.r0 a.m. | 11.5 a.m. o"4 Very slight. 
._. Jf) Slight, but well- 
5 | 0.55 pm. | 2.10 p.m. REA: smarleeel: 
sy | 10.30 p.m. |r 1.10 p.»m.| 11.30 p.m.) About 2 | Gap. 
27 | | 6.35 a.m. 2 r'25 Well-marked. 
1} 915 a.m, {10.50 a_m.| 11.5 a.m. | About 2 | Gap. 3 
oA | 4.10 p.m. | 5-40 p.m. 0'5 Very slight. : 
fl Several almost int 
29 11.20 a.m. } J | perceptible tremors. 
30 | 4-30 p.m, | a irregular inter- 
j vals. “ 
5 | E { No trace of disturb- 
-~j ehe 4-30 ppm. | | \ 4 | ance, but record not 
SEPE 4 DOP Ts \ complete. 
| ee | {| Photographic trace 
4 eens eeeet l a perfectly straight 
6 0.5 a.m. | / ( Pers, 
5-6 | 11.30p.m.| 0.5 a.m. | 0.20 a.m. 2to3 Gap 
6| 2a.m. No dis|turbance here. t 
9 5 {| Well-marked oscilla- 
” beret ee ‘tion. 
The points of special interest in this table are the three 
violent oscillations which have been designated gaps. These 
are complete interruptions in the curve, caused apparently by 
successive waves of sufficient amplitude to produce so rapid an 
oscillatory motion of the pendulum, that the reflected ray 
traverses the exposing slit too quickly to leave any photographic 
trace. The result as seen on the photograph is an abrupt 
termination to the curve line; then for a period of from five to 
ten minutes no photographic effect whatever is produced, and 
for about a similar period, a widened and badly defined trace 
shows that the ray has oscillated to each side of its normal 
position, with an amplitude of disturbance at the time when the 
trace begins to reappear of fully 2”, but which must have been 
considerably greater at the beginning of the gap, where the 
record is altogether wanting. After this the mirror comes to 
rest, and the ordinary trace reappears. 
In the case of all the smaller irregularities of the curve, the 
ray seems to have moved more or less abruptly to a distance 
from its normal position, after which the mirror gradually 
settles to rest. Careful measurements give, for the arc through 
