THE EOYAL AETILLEEY INSTITUTION. 
77 
projecting stud; and on its under side a small cut by means of which it is 
screwed into the body. 
This plug is perforated with two holes : one vertical, through its longer 
axis, to serve as a fire hole through which the flash of the exploded 
detonating composition may communicate with the bursting charge; the other 
horizontal, and intended for the reception of a strand of quickmatch, to 
prevent the powder dust from the bursting charge working into and 
choking the fuze. 
The Lead Cup (Tig. 1, dd) is a hollow cylinder of pure 1 lead, completely 
open at the bottom but having merely a small hole at the top. This cup 
rests upon the bottom plug, the lower part of it adapting itself to the 
rounded form of the interior of the lower part of the body, and thus 
surrounding, though not touching the stud of the bottom plug. 
The Cone Plug (Fig. 1, ee) is made of rather a harder alloy than the body 
of the fuze 2 for a reason which will presently appear. 3 
It is called the “cone” plug from the top edge being bevelled, which gives 
the upper part of the plug a conical form; otherwise it is a plain cylinder 
which exactly fits the interior of the body. From the lower side of the plug 
projects a stud similar to that upon the bottom plug; and the plug is 
perforated vertically with a fire hole. 
The cone plug rests upon the lead cup, its stud entering the small hole in 
the top of the cup. 
The Detonating Ball (Fig. 1,/) is a solid sphere of the same alloy as 
the cone plug, it is roughened, or “ milled,” over its surface and a groove is 
cut round its horizontal circumference, for the double purpose of allowing a 
greater quantity of detonating composition to be placed upon the ball and of 
giving that composition a better hold. 
At the extremities of the vertical axis of the ball are two projections; 
the lower one is conical, the upper cylindrical with a small shoulder round 
its base. Bound the neck of each projection is a small groove. The ball 
is plastered over its wiiole surface up to, but not in the grooves at the neck 
of each projection, with the following composition. 4 
Potash, chlorate of . 6 
Antimony, sulphide of... 6 
Sulphur, sublimed . J 
Powder, mealed .. 1 
Damped into a paste with spirits, methylated, 
1 quart; shellac, 112 grains, in the proportion of 
40 minims of the varnish to 100 grains of com* 
position, 
The composition is covered with fine gut skin 6 tied on with silk cord and 
varnished, and afterwards with thin silk 6 similarly secured and varnished. 
1 The purity of the lead is a Very important point, the strength of the cup being calculated upon 
the assumption that the lead employed is perfectly pure, any admixture which may tend to increase 
the strength of the lead Cup would tend to diminish the certainty of action of the fuze with low 
charges; on the other hand, any decrease in its strength Would render the fuze liable to accidental 
explosion. The Cup should weigh between 190 and 200 grains. 
2 The alloy is, copper 7 parts, tin 1 part; or expressed decimally, copper 87*5, tin 12*6. 
8 See p. 79. 
4 This composition is the same as that used for the quill friction tube, with the exception of thd 
varnish. 
8 Sheep’s gut skiin & Sarsenet; 
[vdL, v.] 
8 Sarsenet; 
11 
