400 
NATURE 
[JUNE 20, 1912 
to deal with the pests? An appeal in the daily Press 
has brought us inquiries as to the formation of clubs 
from Newcastle, Darlington, Blackburn, Walsall, 
Burton, Hull, Grimsby, Birmingham, Shrewsbury, 
and Bristol, whilst in the Manchester district such a 
club is already in being. We should be very glad to 
put any of your readers in touch with the local men 
in these districts, or to aid others to form similar 
clubs. Everything we can do to forward the de- 
struction and thinning out of rats all over the United 
Kingdom we shall be only too happy to do. 
Water Hutton, Hon. Sec. 
81, Clarkehouse Road, Sheffield. 
THE PROGRESS OF RADIOTELEGRAPHY.* 
[Ze volume opens with an interesting résumé 
by Prof. Ferdinand Braun of his contributions 
to wireless telegraphy, the paper being, in fact, a 
Nobel lecture delivered in Stockholm in December, 
1909. The first question of importance which the 
author touches on is the invention of the transmitter 
with coupled circuits, i.e. the use of a primary 
with large capacity to excite the aerial by induc- 
tion instead of charging the aerial directly as 
was done by Marconi at that date. Prof. Braun’s 
historical notes are interesting in connection with 
recent litigation in this country. Among other 
researches which he describes, the most important 
are probably those on directive telegraphy. He 
ends with a quotation from his first lecture in 
1900 :— 
Wireless telegraphy has so far been called spark- 
telegraphy, and no doubt it has hitherto been impos- 
sible to avoid having a spark in some part of the 
apparatus . . . what I have attempted to attain is, 
however, what one might call sparkless telegraphy. 
The first number also contains papers by Prof. 
J. H. Nicholson, P. Barreca, and H. Rau. The 
substance of Nicholson’s paper has already been 
published in English. In Barreca’s paper we have 
a description of a method of measuring the radia- 
tion from an antenna and instances of the applica- 
tion of Barkhausen’s method of using a Braun’s 
oscillograph for the determination of the power in 
a high-frequency current circuit. The chief result 
is a measurement of the sum of the ohmic resist- 
ance and radiating power of a particular station, 
and a proof that for geometrically similar antennas 
the non-ohmic part remains constant. 
H. Rau gives interesting photographic records 
of the primary and secondary discharges in 
ordinary spark telegraphy and in shock excitation. 
In the practical section of this number the greater 
part of the space is given to descriptions, in con- 
siderable detail, of the new Telefunken system 
and recent Marconi apparatus. 
Among papers throughout the volume on the 
transmission of electrical waves over the earth’s 
surface are those by Somerfeld, Epstein, Schmidt, 
and Uller. Somerfeld’s paper is one of the most 
important that has hitherto been published on this 
subject. The whole question of the effects of 
different characters of earth surface in the pro- 
pagation of electrical waves is very thoroughly 
1 ‘* Jahrbuch der drahtlosen Telegraphie und Telephonie.”” Unter beson- 
derer Mitwirkung von. Prof. Dr. J. Zenneck. Herausgegeben von Dr. G 
Eichhorn. Band 4, Heft 1-6. Pp. 664. (Leipzig: J. A. Barth, 1910-11.) 
Price 20 marks 
NO. 2225, VOL. 89] 
discussed, among other things the question of 
surface waves and waves in tree space being satis- 
factorily worked out. 
Epstein contributes a method for determining 
the actual lines of force propagated over various 
soils, with diagrams showing their forms in 
several cases; while Schmidt deals with experi- 
mental measurements of the resistance of sea- 
water in the North Sea, and Uller extends these 
to the Baltic, giving conductivities in terms of a 
formula in which the variable is the concentra- 
tion of sodium chloride. 
The volume contains a number of interesting, 
articles by Nesper and others on detectors, and 
there are numerous papers on methods of measure- 
ment by various authors. The papers dealing 
with the production of high-frequency current are 
mainly concerned with the shock-excitation 
method, with the notable exception of those 
dealing with Goldschmidt’s alternator. 
In addition to Rau’s article, mentioned above, 
there is a paper by Max Wien on shock-excitation 
with quenching tubes, i.e. vacuum tubes in series 
with the spark-gap in the primary, or shock, cir- 
cuit. The result is an increase of primary damp- 
ing and of efficiency. Nesper discusses the 
employment of shock-excitation for wireless tele- 
phony, and particularly the advantages of a con- 
trolled exciter giving a uniform spark rate over 
an irregular discharge. A paper by Eccles and 
Makower on the efficiency of quenched spark 
methods and a number of smaller articles com- 
plete the contributions on this subject. 
Goldschmidt gives an exceedingly interesting 
description of his remarkable high-frequency 
alternator, and Rausch discusses it from the 
mathematical point of view. 
There are a number of articles on a subject 
which has recently been very rapidly developed in 
practice, viz., the transmission of musical tones 
and methods of acoustic tuning for the improve- 
ment of selectivity. Abstracts of patent specifica- 
tions, reviews, and notes on practical problems 
are also included, and the whole volume forms 
an excellent review of the year’s progress in 
technical matters. 
In quality and arrangement of the matter, as 
well as in printing and illustration, the “ Jahrbuch ” 
attains a very high standard. The only criticism 
which suggests itself is whether its utility and 
circulation would not be considerably increased if 
space could be found for more articles dealing 
with the engineering and even the commercial 
side of wireless telegraphy. At present the con- 
tents are largely academic in character, and are 
mainly theoretical and experimental investigations 
into first principles rather than discussions of 
actual problems and what has been accomplished 
towards their solution. A certain number of 
engineering notes are given, and it is the amplifica- 
tion of this section that appears advisable to the 
present writer, so that it may include not only 
descriptive matter, but also discussions of the 
problems occurring in everyday engineering 
practice. J. Ersxine-Murravy. 
