406 
contributes a catalogue of 528 destructive earth- 
quakes in China from B.c. 1831 to A.D. 1911. In all 
the principal districts they are most frequent in the 
summer months, a fact which Mr. Drake attributes 
to rapid and strong variations of atmospheric 
pressure, assisted by the heavy rain-storms which 
occur in summer. The enormous loss of life 
attributed to some earthquakes (such as more than 
830,000 in 1556) is probably exaggerated, but Mr. 
Drake remarks that it may not be greatly over- 
stated. The dense population is grouped in closely 
built cities, the houses are usually built of brick or 
stone, and are roofed with heavy tiles or earth, which 
becomes soaked after long-continued rains. 
Tue Aéronautical Society has issued, in the form 
of an illustrated pamphlet of fifty-two pages, a short 
history of the society from the date of its foundation 
(1866), combined with an account of the progress of 
aéronautics during that period. Many books have 
been written in which the latter subject is treated in 
a popular way, but an exposition tracing the connec- 
tion of our Aéronautical Society with these develop- 
ments is a useful addition to the list. In view of the 
recent death of Mr. Wilbur Wright, the sections deal- 
ing with the work of the Wright Brothers are 
interesting. As a matter of fact, the original Wright 
experiments received little credence in this country, 
and the principal authentic records of them were, it 
is here stated, contained in a letter to Mr. Patrick G. 
Alexander in 1905. It is perhaps unfortunate that 
popular attention was directed to the feats of later 
aviators before the authenticity of these previous 
flights was generally admitted. 
In a paper on the methods of measuring associa- 
tion between two attributes (Statistical Journal, 
Ixxv., 6), Mr. G. Udny Yule considers the inter- 
pretation of data such as the following :—In a small- 
pox epidemic at a place—say, Sheffield—given the 
numbers of recoveries and deaths among vaccinated 
and unvaccinated patients, to find a measure of the 
association between vaccination and recovery. The 
author shows that the ordinary test fails to give con- 
sistent results in comparing different sets of observa- 
tions, say, at Sheffield and Leicester, and he pro- 
poses to interpret them by constructing a ‘‘sym- 
metrical table’ from the observed data. If the 
values of these data be denoted by fp, q, 7, s, the 
numbers in this table are proportional to the square 
roots of ps and gr, and the measure of association 
derived from the symmetrical table will thus be a 
function of the ratio of the ratios of p to q and r to s, 
as it should be. The investigation, however, covers 
a much more extensive ground than this, and allied 
investigations by Pearson and Heron are criticised 
at considerable length. 
Tue April number of the Journal of the Royal 
Meteorological Society contains a description of a 
new dew-gauge by Mr. S. Skinner, which appears to 
be both effective and simple. It consists of a Dewar 
vacuum goblet enclosed in a box, the top of which 
is flush with the edge of the goblet. When exposed 
NO. 2225, VOL. 89| 
NATURE 
[JUNE 20, 1912 
at night the inside surface of the goblet cools by 
radiation and the moisture in the air in contact with 
it is deposited on the glass. In the morning the 
diameter of the drop of water collected at the bottom 
of the goblet is measured with a pair of compasses, 
and the volume of the drop determined by reference 
to a curve. The instrument is used in conjunction 
with a rain-gauge, so that a proper allowance may 
be made for water entering it as rain. As the result 
of observations made during 1909 and 1g1t it appears 
that from 1 to 2 in. of dew falls in this country in the 
course of a year. 
Pror. Prancx’s address to the German Chemical 
Society on December 16, 1911, has been published 
separately by the Leipzig Akademische Verlagsgesell- 
schaft. After showing how the two laws of classical 
thermodynamics lead to an expression for the change 
of the energy of a body in terms of the heat absorbed 
and the work done on the body, Prof. Planck ex- ~ 
plains how, when changes take place at constant 
temperature, the ‘‘free energy”’ of Helmholtz, and 
when, in addition, the pressure is constant, the 
‘thermodynamic potential’’ of Duhem, serve as the 
most convenient means of investigation. He then 
describes the theory introduced by Nernst six years 
ago that the entropy of a body at the absolute zero 
of temperature is zero, and shows how this leads to 
several further conclusions which have been verified 
by observation. In the last section of the address he 
announces that he has given up the idea of the atomic 
structure of energy, and has substituted for it the 
idea that the range from zero to unity of the prob- 
ability of the condition of a material system is divided 
into discreet ranges each of finite length. 
TuHE Society for Promoting Christian Knowledge 
has added to its ‘“‘Romance of Science Series"’ a 
volume entitled ‘‘Chemical Research in its Bearings 
on National Welfare.” The book is written round 
the lecture delivered on January 11, 1911, by Prof. 
Emil Fischer, of the University of Berlin, on the 
occasion of the inauguration of the Kaiser-Wilhelm- 
Gesellschaft zur Foérderung der Wissenschaften, in 
the presence of the German Emperor. The lecture 
was printed in Nature of February 23, 1911 
(vol. Ixxxv., p. 558), and is utilised in the volume 
before us. The editor provides an introduction, in 
which the importance of scientific research to national 
well-being is insisted upon, and a running commen- 
tary to the paragraphs of the lecture serves to give 
the general reader an admirable view of the import- 
ance of progress in chemical science. 
IN a paper read before the Manchester Geological 
and Mining Society, and recently published by the 
| Institution of Mining Engineers, Dr. John Harger 
makes some novel suggestions for the prevention of 
explosions in mines. He states that in discussions on 
the effect of coal dust in causing explosions, although 
in such explosions two factors are concerned—the 
composition of the dust and that of the air surround- 
ing it—attention has been unduly concentrated on the 
former, and the influence of the surrounding atmo- 
