50 NATURE 
[May 19, 1870 
The chief condition to be fulfilled in the construction 
of an electric fuze was the preparation of a compound 
which should combine high conducting power with great 
susceptibility to ignition, and this, after patient and 
renewed investigation, was ultimately accomplished. A 
mixture of subphosphide of copper and subsulphide of 
copper with chlorate of potash afforded a composition 
which was exploded with perfect ease and certainty by a 
current from a small magneto-electric machine, a larger 
apparatus of the same kind being capable of igniting 
twenty or thirty of these fuzes almost instantaneously. 
The means at command afforded, under certain circum- 
stances, by a Wheatstone Exploder and the Abel fuzes, 
can scarcely be valued too highly, and it has been stated 
that the Governor of Malta, if provided with these 
valuable aids, might by himself conduct the defence of 
Valetta Harbour from his own drawing-room window. 
This may indeed be a vainglorious boast, but as a matter 
of hard fact we may mention that the Time Guns at 
Newcastle, Edinburgh, and other northern towns, have 
been ignited for some years past from Greenwich Obser- 
vatory, through many hundred miles of wire, by an Abel 
fuze with infallible precision and certainty. 
Svelion 
Perspeciive view 
ABEL FUZE 
@, cap of composition, into which the two poles of the wires are fixed. 
46, metal eyes for connecting the insulated wires with the fuze. 
Since the date of theseimprovements, much further expe- 
rience has been gained in regard to the most suitable 
description of apparatus to serve as exploders, frictional 
and dynamo-electric machines, as also miniature voltaic 
batteries taking the place of the Wheatstone instrument ; 
the electric fuze has however stood its ground in spite of 
many rivals, and still continues to be used for the ignition 
of explosive charges, including torpedoes and submarine 
mines. 
As mentioned in the first part of this paper, the 
Americans employed electricity for firing some of their 
torpedoes, but they are by no means the only nation who 
has done so. In the Austro-French war, when the 
capture of Venice was feared by the Austrians, a very 
ingenious system of electric torpedo defence was organised 
Y at that seaport by a distinguished officer of Engineers, 
Colonel von Ebner. A camera obscura was erected in 
proximity to the harbour in such a manner that the 
horizontal table of the instrument reflected the whole area 
of the channel. Large wooden cases, each containing 
. 400 pounds of gun-cotton, were lowered at certain fixed 
distances into the water, and as these disappeared one by 
sone, a small row-boat described at the time a circle round 
the spot to indicate the extreme confines of the distance 
at which the torpedo would prove effective ; an observer 
was stationed in the camera as these operations were 
going on, carefully watching their reflection in the instru- 
ment, and as each torpedo disappeared into the water, he 
marked with a pencil its precise locality on the white 
table, tracing also the ring formed by the row-boat. 
Thus a series of circles was formed in the camera, each 
of which was marked with a distinctive number, and in 
this way a miniature, but exceedingly correct, plan 
of the obstructions in the harbours was prepared; the 
wires in connection with the torpedoes were afterwards 
led up into the camera obscura and furnished with 
numbers to correspond with the circles. 
this arrangement a sentinel stationed in the apparatus 
might at once explode any one of the torpedoes, as soon 
as he observed the reflection of an enemy’s ship pass 
within the limits of the circles marked upon the table. 
The channel itself was quite clear of any suspicious buoys 
and beacons, and appeared to the enemy wholly free 
from obstruction, 
SURFACE OF WATER 
GUN-COTTON ELECTRIC TORPEDOES CONSTRUCTED AT VENICE IN 1859 
In our own country the question of torpedo warfare has 
for some years past been the subject of study and inves- 
tigation, and a system has lately been elaborated which 
owes its origin mainly to Mr. Abel, the scientific referee 
of the War Department, and which is at once so simple 
and practical that it cannot fail, in the future, to form 
a new and interesting branch of war science. 
Mechanical torpedoes present so many serious defects 
(as for instance their liability to get out of order, the risk in- 
curred in mooring them, and the danger they involve, when 
once sunk, to friend as to foe), that all idea of their employ- 
ment was at once abandoned by our authorities, and the 
investigations confined to the devising of efficient electric 
torpedoes. Of these many descriptions have been de- 
signed, but the two kinds held most in favour are the 
self-exploding instruments, and those which are capable 
of sending a signal when touched by a passing vessel to 
indicate the proper time of effecting their ignition from 
the shore. 
The self-acting electric torpedo is of very simple con- 
struction, the following being a general outline of one form 
of it. An Abel fuze is fixed in the torpedo, one pole of 
which is connected to a constant battery on shore by means 
By means of — 
aie” 
