AuGust 13, 1897.] 
agreeable contrast to that found in similar man- 
uals. The calculation of corrections and the 
discussion of the effect of the errors of obser- 
vation upon the result, as well as the methods 
of least squares and of approximation, will be 
found particularly clear, complete and useful. 
Indeed, much of the unique value of the book 
lies in its many suggestions as to simple ma- 
nipulative methods, receipts and general good 
advice. It is these little ‘tricks of the trade’ 
that distinguish the successful experimental in- 
vestigator from the helpless theorizer. 
The body of the book contains concise, clear 
instructions for the determination of about 
every quantity that may be of interest to the 
experimental physicist, together with numerous 
demonstrations and illustrative examples. An 
excellent feature of this part is the frequent 
reference to the original investigations from 
which the methods were derived. 
The absolute system of units is happily not 
the novelty to-day that it was when Kohlrausch 
introduced it into the Leitfaden ; nevertheless 
his clear and complete exposition of its princi- 
ples, its units and their values is very accepta- 
ble even now, and gives in some twenty pages 
the essentials of the whole matter. 
The thirty pages of carefully selected tables 
form a very agreeable and striking contrast to 
some similar books recently offered in this coun- 
try. 
Some teachers have lamented the absence of 
pictures of instruments, but it would appear 
inconsistent with the general nature of the book 
if specific pieces of apparatus were represented. 
It is better and probably easier for a pupil to 
specialize from a diagram to any corresponding 
instrument than from one instrument to another 
of radically different appearance, though simi- 
Jar in principle. : 
The English translation of the last edition of 
Kohlrausch is very good, but not so good as 
the original because the translator has permit- 
ted himself to make changes. 
A Systematic Treatise on Electrical Measurements. 
By HERSCHEL C. PARKER. Spon & Chamber- 
lain, London and New York. 
Mr. Parker, confining himself to a smaller 
field, and rather to the technical than the 
SCIENCE. 
259 
theoretical aspect of the subject, has succeeded 
in following the good example of Kohlrausch 
and sets forth what such a course should teach, 
rather than what is taught under the conditions 
at Columbia. 
Particularly valuable is the strictly sys- 
tematic way in whieh the subject is treated, 
enabling the student to see at a glance the rela- 
tive merits of different instruments and methods 
for the various measurements of the same class, 
and to choose the apparatus and method best 
adapted to his particular determination. Al- 
though giving the principle and construction of 
the latest forms of electrical measuring instru- 
ments, the author has done better than some 
others, who could not resist the temptation to 
use old cuts or introduce trade pictures of ap- 
paratus. His diagrams and outline cuts show 
the fundamental parts most satisfactorily and 
enable the reader easily to imagine the brass 
and hard-rubber accompaniments. The book 
is sure to be useful to the electrical engineer, as 
well as to the investigator, who will gladly 
welcome future editions with the revision and 
additions which the author seems to feel desi- 
rable. 
WILLIAM HALLOCK. 
Bibliography—A Study of Resources. CHARLES 
SEDGWICK Minor. In Biological Lectures de- 
livered at the Marine Biological Laboratory of 
Wood’s Holl in the summer session of 1895. 
Boston, Ginn & Company. 1896. P. 149-168. 
Short surveys of the present standpoint of 
bibliography from the point of view of the 
special sciences should prove advantageous 
both for the specialist and for the bibliographer. 
To the former such surveys would be mainly 
useful in giving him a systematic guide through 
the mass of publications which he must work 
over to find the particular literature needed for 
his investigations. To the latter—I am here 
thinking especially of the librarian—they would 
make plain the connection of bibliography with 
the special sciences of which bibliography isthe _ 
handmaid. Professor Minot’s account of biolog- 
ical bibliographical literature is a good example 
of what such a survey should be. He does 
not drown his subject in enumeration of de- 
tails, but describes and considers the main 
