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POPULAR SCIENCE REVIEW. 
coated with lead, which is applied by placing the shell in a mould and 
pouring melted lead round it. # The lead is allowed to percolate among the 
segments, so as to fill up the interstices, the central cavity being kept open 
by the insertion of a steel core. In this state the projectile is so compact 
that it might be fired through six feet of hard timber without injury, while 
its resistance to a bursting force from within is so small that less than one 
ounce of powder is sufficient to break it in pieces. 
The segmental pieces act like the voussoirsf of a bridge iii ' 
fact, in strengthening the shell ; but are easily liberated, when 
they are very destructive. This same projectile can be used 
as a shell ; by leaving out the bursting 1 charge, as a shot ; by 
arranging the fuze so as to burst it as it leaves the muzzle 
of the gun, as common case ; or, lastly, by arranging the fuze 
to burst it just before reaching the object, as shrapnel. Such 
simplicity of ammunition, which further enables one gun to 
fulfil all purposes of gun and howitzer, is of the very greatest 
advantage. Two descriptions of fuzes are used by Sir W. 
Armstrong; the one a percussion fuze for use when it is in- 
tended to burst the shell on striking an object ; the other, a 
time fuze, to explode it at any given length or time of range, 
without its striking an object, as when used as case or shrapnel. 
It must be remembered that the gam is a breech-loader, and that 
there is no windage by which the gas or flame of the powder 
can, as with ordinary guns, get round the shot and ignite the 
fuze. The latter has, therefore, to ignite itself at the instant 
of discharge. This is effected by a percussion arrangement ; 
the rest of the fuze being very much on Breithaupt’s principle. 
Sir W. Armstrong thus describes his fuze : — 
The body of the time fuze (fig. 3) is made of a mixture of lead and tin 
cast to the required form in a mould. The fuze composition is stamped into 
a channel forming nearly an entire circle round the body of the fuze, and is 
afterwards papered and varnished on the external surfaces. As the shell 
fitted accurately into the gun, there was no passage of flame by which the 
fuze could be ignited. The effect is, therefore, produced in the following 
maimer : — A small quantity of detonating composition is deposited at the 
bottom of the cylindrical cavity in the centre of the fuze, and above this was 
placed a small weight or striker, terminating in a sharp point presented 
downwards. This striker is secured in its place by a pin, which, when the 
gun is fired, is broken by means of the vis inertia? of the striker. The deto- 
nator is then instantly pierced by the point, and is thus fired. The flame 
* Mr. Bashley Britten’s plan of joining the lead to the iron by an interior 
skin of zinc is, we believe, now adopted. 
t The voussoir is the technical name given to the w r edge-shaped stones 
which constitute an arch. 
