518 
NATURE 
[ Marcu 31, 1904 
period of the investigations the committee has realised that 
fitting turbines of the dimensions necessary to propel the 
new Cunard ships at the speed contemplated involves a very 
great step in marine propulsion, the largest turbines at 
present in use afloat being those in the steamship Queen, 
engaged on the Calais-Dover service. 
We have received a copy of Deutsches Meteorologisches 
Jahrbuch fiir 1902, containing the results of the meteor- 
ological observations at the stations under the control of 
the Deutsche Seewarte. This is the twenty-fifth annual 
volume of this very valuable publication, and forms, as our 
readers are aware, but one portion of the useful work that 
falls to the share of the establishment in question. We 
need hardly mention how actively the Seewarte is engaged 
in the prosecution of weather telegraphy and ocean meteor- 
ology ; it is probably not so well known that, in conjunction 
with the Danish Meteorological Institute, it publishes a 
most laborious series of daily synoptic weather charts for 
the North Atlantic Ocean, in quarterly volumes, which | 
furnish a valuable aid to the study of the cyclonic systems 
that form so important a factor in the weather conditions 
of western Europe. The Jahrbuch referred to above con- 
tains a summary of all the storms which visited the German | 
coasts in 1902, compiled from the registers kept at the 
storm signal stations in connection with the Seewarte; we 
think this by no means light compilation is an important 
appendix to the work. 
A COMMUNICATION has been received from Mr. A. Apps in 
which he desires to point out that the claim of anything 
new or special can hardly be sustained in respect of the 
interrupter referred to in our note on p. 470 (March 17). 
He states that in or about 1858 the late Mr. Ladd made 
a contact breaker for Mr. J. V. Gassiott, F.R.S., in which 
the hammer was so arranged as to knock away the contact 
between the platinum studs very suddenly; this coil gave 
12 inch sparks, but when fitted by Mr. Apps with one of 
his ro inch contact breakers in 1899 a 14% inch spark was 
obtained. Another interrupter on the Gassiott model, made 
for Mr. Baines in 1868, was discarded after many experi- 
ments. About 1866 a coil designed by Cromwell Varley, 
F.R.S., was fitted with a hammer arranged to produce a 
very sudden break, and this also was replaced a few years 
later by one of the Apps form. Mr. Apps further states 
that for the last thirty years it has been usual for his coils 
to give a ro inch spark with 2 cells (4 volts), and that he 
has now a coil giving 12 inches freely with a 2 cell storage 
battery. It may be added that our remark as to the new 
arrangement performing what the inventors claimed re- 
ferred rather to the length of spark obtained with a given 
battery power than to its merits compared with other forms, 
and it should have been stated that while the 10 inch spark 
was obtained with the greatest ease from two four-volt 
storage cells, even an electromotive force of four volts was 
capable of producing a spark of this length. 
Ix a couple of short printed notes Prof. Moriz Kuhn, of 
Vienna, describes simple apparatus adapted for class-room 
demonstrations of Torricelli’s theorem, Boyle’s and 
Dalton’s laws, and other properties of gases. With a slight 
modification, a very fair vacuum tube can be obtained with 
one of the apparatus, or it can be used as an open tube 
manometer. The whole apparatus is made by 
Woytacek, 10 Frankengasse, oth district, Vienna. ; 
Karl 
Messrs. VIEWEG AND Son, of Brunswick, have issued a 
fourth edition of vol. i. part iii. of Dr. Alex. Wernicke’s 
“Lehrbuch der Mechanik.’’ It forms a complete treatise 
NO. 1796, VOL. 69] 
on the theory of elasticity as applied to engineering 
problems, and deals at considerable length with the statics 
of loaded beams. In this part of the subject considerable 
use is made of graphic methods. The book is peculiarly 
adapted to students of German technical schools, but it 
also meets the requirements of certain university students 
and candidates for higher teachers’ certificates in that 
country. It covers a field of study which does not receive 
the attention which it ought to have in this country ; prob- 
ably no English text-book exists which is written on the 
same It should receive the careful attention of 
lecturers on applied mechanics. 
lines. 
A PRELIMINARY report on the lead and zinc deposits of 
south-western Wisconsin, by Prof. U. S. Grant, has been 
issued as Bulletin No. 9 of the Wisconsin Geological and 
Natural History Society. In order to render the work useful 
to the public in general, there is a popular account of the 
physical features, geology, and genesis of ore deposits, 
occupying half of this little volume. The lead and zinc ores 
occur in Cambrian, but mainly in the Trenton and Galena 
Limestones of the Ordovician. The original minerals of 
the ore-deposits are the sulphides, galena, sphalerite and 
marcasite. Smithsonite and iron oxides are secondary 
minerals, having been formed from the alteration of the 
original sulphides. The secondary minerals occur in the 
rocks above the level of ground water, or in the belt of 
weathering. The original minerals, with the exception of 
galena, which is closely associated with both the original 
and secondary minerals, occur below the level of ground 
water. The order of deposition is noted as (1) marcasite, 
(2) sphalerite (sometimes with galena), (3) galena. The 
author points out the method of occurrence of the ores, and 
explains their origin as due partly to deep-seated or artesian 
circulation of water, and partly to down water circulation. 
The methods of mining and the resources of the area are 
duly considered. 
Tne March number of the National Geographic Magazine 
deals chiefly with Manchuria and Korea. A good war 
map, with insets, prepared by the American War Depart- 
ment, is included, and there is a specially valuable account 
of Russian development of Manchuria by Mr. Henry B. 
Miller, United States Consul at Niuchwang. 
Except for a note by Mr. D. W. Freshfield on the road 
to Tibet, the current number of the Geographical Teacher 
is chiefly devoted to reports of the proceedings of the Geo- 
graphical Association, of conferences on the teaching of geo- 
graphy, and to reprints of papers read. The discussion on 
the Royal Geographical Society’s syllabus, by experienced 
school teachers of the subject, is of special interest and 
value. 
Tue February number of La Géographie contains articles 
on the Lenfant expedition, which has discovered a con- 
tinuous watercourse between the Logone and the Benoué, 
i.e. between the Tchad and Atlantic basins; on the explor- 
ation of Bolivia; on the province of Bathang; and on the 
country of the Hereros. There is also a number of 
valuable notes, including one on the utilisation of water- 
power in la Mayenne and la Manche, and another on the 
present state of the Russian geodetic and topographic 
surveys. 
WE learn from the Bulletin of the Society of Naturalists 
at St. Petersburg (No. 1) that a new expedition for the 
exploration of the Caspian Sea is to be sent out early this 
spring. It is a continuation of the Aral-Caspian expedition 
which worked some thirty years ago. The party will 
