May 19, 1870] 
NATURE 
51 
of an insulated wire, while the other pole is in communi- 
cation with an insulated metal plate fixed inside a pivot 
in the upper part of the machine. Upon this pivot swings 
a moveable hood, or cage, and the latter, though not 
affected by the motion of waves, will, upon being struck 
by a passing vessel, swerve round and come into metallic 
contact with the insulated plate above mentioned, thus 
completing the electric circuit with the earth, or, more 
strictly speaking, with the water. As will be readily per- 
ceived therefore, in this case, a single wire only is needed 
to connect one element of the battery with the fuze, the 
other element being of course allowed to pass to earth. 
In the other description of torpedo, a circuit closer of the 
same construction is used, and this on being struck furnishes 
a signal to the shore, whence a sentinel at once explodes 
any charge, or charges, which may be in the vicinity of the 
submerged machine. When disconnected from the bat- 
teries, these torpedoes naturally cease to be a source of 
danger, and herein lies one of the most valuable qualities 
of the electric exploding method. If considered desirable, 
the machines need in fact never be put into an active state 
except in a case of imminent danger. Thus, if a fleet of 
friendly vessels were pursued by hostile ships, the sentinel 
on the look-out would not connect his batteries until the 
former had passed over the torpedoes, and when the 
machines were well left behind, by simply turning a switch 
arrangement he would be enabled instantly to close the 
line of defence, and set up a formidable barrier not to be 
passed with impunity. 
In the simplest form of electric torpedoes (such as the 
majority of those used in America) where ignition is 
brought about by simply sending a current through the 
circuit, one wire leading from the torpedo to the battery 
and another to earth, the employment of the Abel fuze 
presents one very important advantage. Explosive 
machines fitted with these appliances may, when in posi- 
tion, be tested at any moment to ascertain their state of 
efficiency, and the operator is thus made cognisant of the 
serviceableness or otherwise of his apparatus and _ bat- 
teries ; this operation is effected by simply passing a weak 
current through the wire and fuze, which although insuffi- 
cient to produce ignition, is yet powerful enough for the 
transmission of signals. 
Where a large number of torpedoes are grouped to- 
gether, it is found undesirable, except in special cases, to 
use either the frictional or dynamo-electric machines for 
exploding the fuzes, for the reason that a current sent from 
one of these instruments to ignite a specific charge, in- 
duces similar currents in adjacent wires and at once causes 
a wholesale explosion. Constant voltaic batteries or piles 
are therefore generally resorted to, and the construction 
of simple forms of these from rough, handy materials 
_(some sheet zinc and copper, a few pieces of wood, and a 
little vinegar and common salt) is a favourite occupation 
among sailors who have received elementary instruction 
in this system of warfare. 
By employing in torpedoes, instead of powder, a heavy 
charge of gun-cotton, and exploding this by the newly- 
discovered method of detonation, a force is developed 
which, it is no exaggeration to say, would prove fatal 
against a vessel of the strongest and most cunning con- 
struction. : 
NOTES 
Weare glad to be able to announce that the arrangements for the 
Eclipse Expedition are progressing very rapidly and satisfactorily, 
and that there seems every chance of everything being done which 
can insure success. In response to their circular, the Council of 
the Royal Astronomical Society have received upwards of sixty 
applications from observers anxious to help in an examination 
of the phenomenon. It is proposed that, if possible, there 
s 
shall be two expeditions; one to Spain, the other to Sicily. The 
desirability of this is obvious, as the chances of bad weather are 
thereby considerably reduced. Unfortunately, those who know 
Sicily well state that the region to be visited is so brigand- 
ridden that other precautions besides those usually employed in 
Eclipse Expeditions will be desirable. The Italian Government, 
which will also, we believe, send an expedition to Sicily, will, 
doubtless, look to this. The French Expedition will observe 
in Algeria, 
Our Berlin Correspondent writes that Baron Liebeg has re- 
covered from his recent severe illness. 
WE regret to learn that Mr. Archibald Geikie, who recently 
left England to investigate the Geology of the Lipari Islands, 
was prostrated by fever as soon as he arrived there, and is in 
such a weak state of health, that he has been ordered back to 
England. 
AN Imperial decree has been published in Paris, ordering that 
the Minister of Fine Arts shall henceforth bear the title of Minis- 
ter of Literature, Science, and Art, and also that his department 
shall include the superintendence of the Institut de France, 
Academie des Sciences, the libraries, learned societies, and the 
like. When shall we get ow, Ministry of Literature, Science, 
and Art? 
Tus will be a week of Anniversary Meetings. On Monday 
the annual reunion of the Royal Geographical Society will be 
held at one o’clock, and of the Victoria Institute at four; and 
on Tuesday the Linnean Society will celebrate its anniversary at 
three, and the Ethnological at four. 
THE British Medical Journal states that the chair of Phy- 
siology, in the University of Prague, vacant by the death of the 
celebrated Purkinje, has been filled by the appointment of Dr. 
Hering, of Vienna. It was offered to Professor Helmholtz, who, 
however, preferred to remain at Heidelberg. 
Ar the annual meeting of the Newcastle Natural History 
Society on the roth inst., a discussion took place on the present 
position of the Alder Memorial Fund. It was stated that while 
the original intention was to raise 600/. to carry out the memorial 
scheme, only about 300/. had been collected since March 1867. 
After some discussion, it was agreed to make efforts to raise an 
additional 100/., which was considered a sufficient sum to carry 
out the objects proposed. 
AT the recent general examination for women, held by’ the 
University of London, five passed in the ‘‘ Honours” Division 
and four inthe First Division. Of the seventeen candidates, five 
were from the Cheltenham Ladies’ College, all of whom were 
successful, two being placed in the Honours and three in the 
First Division. 
Mr. J. W. Etwes, of King’s College and the London 
University, and Mr. W. T. Sollas, of the Royal School of 
Mines, have been elected (equal) Exhibitioners in Natural 
Science, at St. John’s College, Cambridge. There were eight 
candidates ; the examiners being Prof. C. C. Babington (Botany), 
Prof. Humphry (Physiology), Prof. W. G, Adams (Physics), 
Mr. Bonney (Geology), and Mr. Main (Chemistry). 
A RECENT number (94) of the German series known as ‘‘ A 
Collection of Popular Scientific Treatises, edited by R. Virchow 
and Fr. von Holtzendorff,” is a lecture on the Glacial Period (Die 
Exszeit der Erde), by Alexander Braun. It gives a clear and 
concise history of the observations and arguments by which 
geologists have been led to the conclusion that a lengthened 
period of extreme cold overspread the greater part of Europe 
before the commencement of the historical epoch. 
Mr. C. P. SMITH reprints, as a separate publication, an 
epitome of a paper read before the Brighton and Sussex 
