THE ROYAL ARTILLERY INSTITUTION. 
193 
PERCUSSION FUZE, 
DESIGNED FOR AND ADAPTED TO THE FORM OF CASE USED FOR SHELLS FOR 
RIFLED GUNS FOR FIELD SERVICE, 
BY L1EUT.-COLONEL FREETH, R.A. 
A description has been given of the percussion fuze,* designed by Major 
Dyer, R.A., and as the subject is treated in a very lucid manner by Capt. 
Majendie, R.A., I take the liberty of adopting a similar mode of detailing 
the construction of the interior (or fuze proper) proposed by me. 
This fuze consists of the following parts : the body 
or case, the hammer, the pellet, the cup for guarding 
detonator, the cup for supporting hammer, the washer 
for fire-holes, the disc for bottom, and the needle. 
The body or case is completed with the several 
parts appertaining to it in the same manner as 
described in the paper alluded to; the dimensions 
are similar, the only difference being that the sides of 
the case are not perforated. 
The hammer is made of the same alloy as the body, and the interior of it 
is bored slightly conical and roughed with six slight Y-shaped grooves; the 
upper part is cupped out to admit the cup for guarding the detonator; three 
grooves or air passages are cut at equal distances on the parallel part of the 
hammer; and the lower end is coned or slightly chamfered to facilitate its 
descent on the lower cup which supports it until the gun is fired. 
The exterior of the pellet, which is made of well seasoned boxwood, is 
turned to the same cone as the interior of the hammer, the neck of it is the 
same diameter as the hole in the cup which guards the detonator contained 
therein. 
The cup for guarding the detonator is made of sheet brass, rolled to the 
thickness of *003 of an inch, and has six fine slits cut out at equal distances 
*1 of an inch long. 
This cup is fitted on to the neck of the pellet when inserted in the ham¬ 
mer, so that it is supported by the hammer, the edges of it being flush with 
the top of the hammer. 
The cup for supporting the hammer is made of sheet brass *005 of an 
inch thick, and perforated at the top, to allow the pellet to pass through it, 
and rests flush with the lower end of the pellet on the bottom of the case 
when screwed home. 
Action of the Fuze. On the discharge of the gun the hammer breaks down 
by the sudden shock the cup which formerly supported it, embracing firmly 
at the same time the wood pellet at the lower end, and also withdrawing its 
support from the cup guarding the detonator; on impact of the shell the 
hammer forces the pellet on the front cup, which being very sensitive in 
* Vide Vol. IV. p. 280. 
