180 
training, are usually excellent, and to the ordi- 
nary student, for whose guidance they were 
evidently more especially intended, they must 
always prove valuable. The drawings of the 
violets, for example, are excellent and helpful 
representations of the different species of that 
group. Inthe case of the genus Myriophyllwm in 
which the drawings have less of sharpness and 
more of the character of sketches, the species, 
which everyone has had difficulty in under- 
standing from mere descriptions, can be readily 
recognized from the drawings. 
Probably the principal fault in the general 
make-up of the work lies in the separation of 
the Latin and English indexes, a system which if 
carried through the third volume would some- 
times make it necessary for one unfamiliar with 
botanical names to look in six different indexes 
in order to find a particular plant. Itis to be 
hoped that the third volume will contain a 
single combined Latin and English index to all 
three volumes. 
The impression is strengthened by this second 
volume that this work marks an epoch in the 
development of systematic botany in America, 
combining, as it does, the best of the new ideas 
which have been current in this country for 
twenty years and which had their source in the 
new method of systematic research in which 
the younger generation had been educated, 
based on the Darwinian ideas of genetic de- 
velopment. 
F. V. CoviLLe. 
SCIENTIFIC JOURNALS. 
TERRESTRIAL MAGNETISM FOR JUNE. 
THE first article, by Dr. J. A. Fleming, on 
‘The Earth a Great Magnet,’ gives a popular 
exposition of the principal phenomena of the 
earth’s magnetism. For many years it has 
been the custom to have a popular experimental 
or illustrated lecture delivered during the meet- 
ing of the British Association for the Advance- 
ment of Science, addressed especially to the 
artisans of the town in which the meeting takes 
place. This article gives the text of the dis- 
course delivered by the author before the work- 
ingmen of Liverpool at the last meeting of the 
British Association. Dr. Fleming’s most ad- 
mirable lecture was profusely illustrated by ex- 
SCIENCE. 
[N. 8. Vor. VI. No. 135. 
periments, and was presented before a very 
large audieyce in the Picton Hall. It appears 
in Terrestrial Magnetism in full for the first time. 
Professor McAdie reviews and summarizes 
the present state of our knowledge with regard 
to ‘The Electrification of the Atmosphere,’ as 
set forth in the recent publications of Chree, 
Elster, Geitel and Schuster. The author thinks 
that there are good grounds for believing that 
the twentieth century will number among its 
triumphs a complete electrical survey of the at- 
mosphere. He regards the question as to the 
relation between the magnetic elements and 
the atmospheric electric currents as the coming 
one. 
Mr. Littlehales gives an abstract of his re- 
cent researches with respect to the establish- 
ment of ‘Secular Variation Expressions of the 
Magnetic Inclination.’ This investigation is pre- 
paratory to a future article which will give the 
secular change in the direction of a freely sus- 
pended magnetic needle at each of twenty-two 
stations distributed over the globe. 
Dr. Bauer, in the next article, ‘A Remark- 
able Law,’ presents formule giving the diurnal 
range of the magnetic declination and inclina- 
tion as simple functions of the magnetic incli- 
nation. The formule were first found empir- 
ically and then deduced theoretically by assum- 
ing that the component of the deflecting force 
producing the angular deflection of the needle 
from its mean position is inversely proportional 
to the force exerted on the needle by the earth’s 
permanent magnetism. The formulz would 
imply that the lines of equal magnetic incli- 
nation represent closely the lines of equal 
diurnal range. The author finds that the same 
functions hold with regard to some of the secu-* 
lar and distribution phenomena of the earth’s 
magnetism. 
In ‘Letters to Editor’ is a communication 
from Professor Hellman regarding Stevins’s 
‘ AIMENYPETIKH ;’ another from Dr. van Bem- 
melen discussing the non-cylic phenomena of 
the diurnal variations, and a third from Drs. yon 
Rijckevorsel and van Bemmelen giving the re- 
sults of their magnetic observations on the 
Rigi, made in 1895 and 1896. 
Abstracts, Reviews, List of Publications and 
Notes close the number. 
