a, 
the subject (both the theoretical principles uvon which the art is based and the practical rules and 
details of technical application on a commercial scale), so that it is suited to the requirements of 
both students and manufacturers, ; 
Heaviside—ELECTROMAGNETIC THEORY. By Oliver Heavi- 
side. Vol. I. Second issue. 466 pages. Price 12s. 6d., post free, 13s. Vol.II. 568 pages. 
Price 12s. 6d., post free; abroad, 13s. Vol. III. in preparation. ‘ 
Extract from Preface to Vol. 1.—This work is something approaching a connected treatise 
on electrical theory, though without the strict formality usually associated with a treatise. The 
following are some of the leading points in this volume. The first chapter is introductory. The 
second consists of an outline scheme of the fundamentals of electromagnetic theory from the 
Faraday-Maxwell point of view, with some small modifications and extensions upon Maxwell’s 
equations, The third chapter is devoted to vector algebra and analysis, in the form used by me 
in former papers. The fourth chapter is devoted to the theory of plane electromagnetic waves, 
and, being mainly descriptive, may perhaps be read with profit by many who are unable to tackle 
the mathematical theory comprehensively. I have included in the present volume the application 
of the theory (in duplex form) to straight wires, and also an account of the effects of self- 
induction and leakage, which are of some significance in present practice as well as in possible 
future developments. : 
Extract Srom Preface to Vol, 1].—From one point of view this volume consists essentially 
of a detailed ‘development of the mathematical hecty of the propagation of plane electro- 
magnetic waves in conducting dielectrics, according to Maxwell’s theory, somewhat extended. 
From another point of view, it is the development of the theory of the propagation of waves along 
wires. But on account of the important applications, ranging from Atlantic telegrapby, through 
ordinary telegraphy and telephony, to Hertzian waves along wires, the Author has usually 
preferred to express results in terms of the concrete voltage and current, rather than the specific 
electric and magnetic forces belonging to a single tube of flux of energy. . . . The theory of 
the latest kind of so-called wireless telegrapby (Lodge, Marconi, &c.) has been somewhat 
anticipated, since the waves sent up the vertical wire are hemispherical, with their equatorial 
bases on the ground or sea, which they run along in expanding. (See 360, Vol. I. ; dso $393 in 
this volume.) The author’s old predictions relating to skin conduction, and to the possibilities of 
long-distance telephony have Theeds abundantly verified in advancing practice; and his old 
predictions relating to the behaviour of approximately distortionless circuits have also received 
fair support in the quantitative observation of Hertzian waves along wires. 
JehI—CARBON ‘MAKING FOR ALL ELECTRICAL PUR- 
POSES. By Francis Jehl. Fully illustrated. Price 10s. 6d. Postage free, This work 
gives a concise account of the process of making High Grade and other Carbon for 
Electric Lighting, Electrolytic, and all other electrical purposes. 
ConTENTS. 
Chapter I.—Physical Properties of Carbon. Chapter X.—Gas Analysis. 
3, II.—Historical Notes. ‘3 .—On the Capital necessary for 
» III.—Facts concerning Carbon. starting a Carbon Works and 
», IV.—The Modern Process of Manu- the Profits in Carbon Manu- 
facturing Carbons. facturing. : 
»  V.—Hints to Carbon Manufacturers 3» XII.—The Manufacture of Electrodes 
and Electric Light Engineers. ona Small Scale. , 
1 _VI.—A “New” Raw Material. », XIII.—Building a Carbon Factory. 
», .VII.—Gas Generators. y XIV.—Soot or Lamp Black. 
», VIII.—The Furnace. x» &V.—Soot Factories, 
», %IX.—The Estimation of High Tem- 
peratures. 
Kennelly and Wilkinson—PRACTICAL NOTES FOR ELEC- 
TRICAL STUDENTS. Laws, Units and Simple Measuring Instruments. By A. E. 
Kennelly and H. D. Wilkinson, M.I.E.E. 320 pages, 155 illustrations, Price 6s. 6d., 
post free. 
. ConrTENTS. ; 
Chapter I.—Introductory. Chapter V1.—Current Indicators, 
TI,—Batteries, VII.—Simple Tests with Indicators. 
EE ee ames Force and Poten- VIII.—Calibration of Current Indica- 
tial. tors. 
ITV.—Resistance. IX.—Magnetic Fields and _ their 
V.—Current. easurement. 
These instructive Practical Notes for Electrical Students were started by Mr. A, E. 
Kennelly tae to his departure from England to join the staff of Mr. Edison in the United 
States, and were continued and completed by Mr. H. D. Wilkinson, who has prepared a work 
which is of great service to students. The volume contains 155 illustrations, and deals mainly 
with Laws, Units and Simple Measuring Apparatus. = 
Lemstrom—ELECTRICITY IN AGRICULTURE AND HORTI- 
CULTURE. By Prof. S. Lemstrém. With illustrations. Price 3s. 6d, nett. 
Extract from Author's Introductory Remarks.—It is well known that the question which is 
the subject ot this book has been a favourite field of investigation for a century past. As the sub- 
ject is connected with no less than three sciences—viz., physics, botany and agricultural physics— 
“THE ELECTRICIAN ” PRINTING & PUBLISHING CO., LTD., 
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