FEBRUARY 22, 1901. | 
and in the discovery of further facts. The sub- 
ject is presented in what seems to me the cor- 
rect perspective, theory being subordinated to 
fact.’? The method of treatment is the inter- 
rogatory one and an effort is made to teach the 
student to observe for himself. While this 
method is an excellent one in theory it is doubt- 
ful whether it can be used with success with a 
class of beginners who have had no experience 
in scientific methods. In the early stages of 
the work they must be taught how to observe, 
and their powers of observation must be trained 
by showing them what they should see in each 
ease. In some cases the important features of 
the experiment might be entirely overlooked 
and unimportant details magnified if the atten- 
tion is not directed to the desired points. Of 
course, this might be overcome by constant 
personal contact with the student ; but such is 
hardly possible in many institutions. 
J. E. G. 
BOOKS RECEIVED. 
Les diastases et leurs applications. E. Pozzi-Escor. 
Paris, Masson et Cie. 1900. Pp. 217. 
Aleyonium. SYDNEY J. Hickson. London, Wil- 
liams & Norgate. 1901. Pp. viii 22. 3 Plates. 
Lehrbuch der vergleichenden Anatomie der wirbellosen 
Thiere. ARNOLD LANG. Jena, Gustav Fischer. 
1901. Pp. vi-+ 311. 
Proceedings of the Iowa Academy of Sciences for 1899. 
SAMUEL W. BEyrER. Des Moines, F. R. Conway. 
1900. Volume VII. Pp. 212. 
Bibliotics or the Study of Documents. PERSIFOR 
FRAZER. Philadelphia, J. B. Lippincott Com- 
pany. 1901. Pp. xxiv 226. 
Thirty-second Annual Report of Births, Deaths, Mar- 
riages and Divorces in Michigan. JUSTUSS. STERNS, 
Lansing, Robert Smith Printing Co. 1900. Pp. 
xvi-+cixxii. Tables, 189. 
Laboratory Companion. W. A. SHENSTONE. London, 
Edward Arnold. 1901. Pp. viii +117. 
Theoretical Mechanics. LL. M. Hoskins. Stanford 
University, Cal., pubiished by the Author. 1900. 
Pp. x +436. $3.25. 
Reservoirs for Irrigation, Water-Power and Domestic 
Water-supply. JAMES Dix ScHUYLER. New 
York, John Wiley & Sons; London, Chapman & 
Hall, Limited. 1901. Pp. xviii 414. 
SCIENCE. 
305 
SCIENTIFIC JOURNALS AND ARTICLES. 
In the January number of the Physical Review 
Theodore Lyman presents the results of a study 
of the ‘false spectra’ often produced by a 
Rowland concave grating. These spectra are 
most clearly seen in the extreme ultra-violet, 
and are shown to be diffraction spectra of much 
less dispersion than the ordinary spectra. They 
appear to be due to errors of ruling, extending 
over the whole surface of the grating. A. A. 
Noyes describes in the same number a modifica- 
tion of the usual method of determining transfer- 
rence numbers, and applies the method toa large 
numberof saltsolutions of varying concentration. 
The application of interference methods to the 
determination of Poisson’s ratio forms the sub- 
ject of an article by J. R. Benton ; while two ar- 
ticles by Chas. T. Knipp deal respectively with 
the employment of the bicyle wheel in illustra- 
ting the principles of the gyroscope, and with a 
new form of automatic temperature regulator. 
The former article describes a number of simple 
experiments with an ordinary bicycle wheel 
which are readily performed, and at the same 
time illustrate very strikingly the properties of 
the gyroscope and gyroscopic pendulum. Ex- 
periments are described by E. C. Roberts to 
determine whether the dielectric constant is 
altered by a magnetic field. The results are 
wholly negative. 
THE January number of the American Jour- 
nal of Mathematics (Vol. X XIII., No. 1), contains 
the following articles: ‘Die Typen der line- 
aren Complexe rationalen Curven im R,,’ by 8. 
Kantor; ‘Transformation of Systems of Linear 
Differential Equations,’ by E. J. Wilczynski ; 
‘Distribution of the Ternary Linear Homo- 
geneous Substitutions in a Galois Field into 
Complete Sets of Conjugate Substitutions,’ by 
L. E. Dickson ; ‘ Distribution of the Quaternary 
Linear Homogenous Substitutions in a Galois 
Field into Complete Sets of Conjugate Substi- 
tutions,’ by T. M. Putnam; ‘On the Deter- 
mination and Solution of the Metacyclic Quintic 
Equation with Rational Coefficients,’ by J. C. 
Glashan ; ‘Construction of the Geometry of 
Euclidean n-Dimensional Space by the Theory 
of Continuous Groups,’ by E. O. Lovett; ‘A 
Table of Class Numbers for Cubic Number 
