692 SCIENCE. 
has made an improvement here, in the arrange- 
ment of the logarithms of numbers in single 
entry. The logarithmic sines and tangents 
are given for every second of are up to 
8° 0’ 0”; and the type of the main trigono- 
metric table, together with its very convenient 
tables of proportional parts, makes this supe- 
rior, on the whole, to any other similar one. 
A material improvement has also been intro- 
duced in the table of addition logarithms. 
The formulae at the end are convenient, and 
not superfluous. They are elegantly arranged 
(see the black-faced type on p. 157, for ex- 
ample), and are such as are always needed. 
The table of constants, as in his six-place 
tables, is very full and most practical. A few 
electrical data might, perhaps, have replaced 
Gauss’ formula for the date of Easter with 
advantage. This is, no doubt, the very best 
five-place table for general use, and exactly 
suited for use with students. 
Topographical surveying. New York, D. Van Nos- 
trand, 1884. (Van Nostrand science series, No. 
12B)) PMO Pee 
Tue four papers which have been repub- 
lished in this book, upon methods in surveying, 
more particularly adapted to topographical 
work, were first printed in Van WNostrand’s 
engineering magazine. The one by George J. 
Specht explains the use of the stadia, with a 
telescope having additional horizontal wires, so 
that distances may be obtained without meas- 
urement. The application of photography to 
topographical surveying, as developed by the 
French engineers, so that the adjustment of two 
or more views of the same objects in a landscape 
to their proper positions on a sheet will enable 
these objects to be platted with their proper 
distances and elevations, is explained by Prof. 
A.S. Hardy. Applications of the geometry 
of position to some problems in surveying are 
given by John B. McMaster,—a method of 
solution which depends upon intersections of 
lines, and does not seem so convenient, ex- 
peditious, or accurate as other methods long 
and well known. The use of rectangular co- 
ordinates for the location and description of 
* _ wy. a ae ie a ee 
[Vou. III., No. 70. 
points is urged and illustrated by Henry F. 
Walling. All of these papers are necessarily — 
brief, but serve to give some useful hints to 
the topographer. A more careful proof-read- 
ing would save a young surveyor from a little 
perplexity in knowing what is meant by some 
statements. 
Dynamic electricity, including, 1°, Some points in elec- 
tric lighting, by Dr. Joun Horxinson ; 2°, On 
the measurement of electricity for commercial pur- 
poses, by JAMES N. SHOOLBRED ; 38°, Electric- 
light arithmetic, by R. E. Day. New. York, Va 
_ Nostrand, 1884. 4+4+167 p. 24°. ; 
Dr. Hopxinson’s lecture before the Institu- 
tion of civil engineers is an excellent treatment 
of the many analogies between the mechanical 
theory of electricity and the science of hydraul- 
ics. The student will find in this lecture a de- 
scription of Maxwell’s apparatus for illustrating 
the laws of induction, which has not found its 
way into any other treatise on electricity. A 
very pretty analogy between the action of the 
hydraulic ram and the extra current of indue- 
tion is also given by Dr. Hopkinson. It is also 
shown how alternating dynamo machines can be 
run on the same circuit in order to assist each 
other, — a problem which has been considered 
by some unsolvable. The equations which illus- 
trate the theory of the dynamo-electric engine 
are grouped together, and their practical use 
ig shown. ‘The author briefly refers to his im- 
provements in the Edison dynamo, and gives 
an estimate of the cost of incandescent light- 
ing. Dr. Hopkinson thinks that the efficiency 
of the carbon-filament lamp will be very much 
increased. ‘These lamps have not been in 
the market more than three years, and it is 
reasonable to suppose that the coming three 
years will see great improvements in them. 
The prospect that the electrical incandescent 
light will be the light of the future seems a 
very good one. 
The paper by Mr. Shoolbred gives an excel- 
lent account of the various meters invented by 
Edison, Sprague, Hopkinson, Boys, Ayrton 
and Perry, and others. Mr. Day’s treatise on 
electric-light arithmetic is a useful one for the 
electrical engineer. 
INTELLIGENCE FROM AMERICAN SCIENTIFIC STATIONS. 
GOVERNMENT ORGANIZATIONS. 
U.S. geological survey, 
Division of chemistry. — Prof. F. W. Clarke is exam- 
ining a collection of waters from the Virginia hot 
springs, and is also beginning a series of experiments 
upon the synthesis of silicates by the wet method. 
— Dr. T. M. Chatard has completed a research upon 
a new method of estimation of alkalies in silicate 
analyses. 
