ARTILLERY. 
The following Table shews the dimensions of heavy, medium, and light brass guns, in 
thirty second parts of their respective calibres. 
Heavy. 
Medium 
Light. 
33 
32 
22 
26 
25 
16 
17 
16 
10 
32 
30 
20 
32 
30 
24 
12 
10 
9 
30 
24 
24 
4 
3 
3 
32 
26 
26 
26 
22 
20 
48 
44 
36 
Thickness of 
metal. 
Trunnions. 
Cascable. 
At the breach and commencement of the 
first reinforce 
End of the first reinforce 
£ Muzzle astragal 
5 Diameter 
£ Length 
From the extremity of the base ring to that 
of the breach mouldings 
From the end of the breech mouldings to the 
centre of the button 
Breadth of the ovalo, or quarter round 
f Of the button 
Diameter < Of the neck 
f Of the last fillet 
In heavy and medium brass guns the first 
and second reinforces are similar frustrums 
of right cones ; and consequently, when pro- 
duced, their outlines will be parallel to each 
other, and are distant one-sixteenth part of 
the calibre. The exterior diameter of the 
piece is also diminished by that quantity, 
and its outline is drawn to the muzzle astra- 
gal. 
In light guns the length of the piece must 
be divided into 18 equal parts, of which 
5 parts are taken for the breech and 
first reinforce ; 
4 parts for the second reinforce ; 
9 for the chase ; 
for the length of the muzzle ; 
| part for the diameter of the neck. 
The axis of the trunnions are 8 parts from 
the breech, and half a calibre below the 
axis of the piece. The position of the trun- 
nions of heavy and medium brass guns is at 
f ths of the length of the piece, from the ex- 
tremity of the breech, and half a calibre be- 
low the axis of the piece, reckoning to their 
centres. The diameter of the trunnions are 
each one calibre, and their length the same, 
allowing for the projection of the second re- 
inforce ring ; their faces are parallel to the 
axis of the piece. The trunnions of medium 
and light brass guns have shoulders, which 
are a tenth of the diameter of the trun- 
nion in breadth, and of sufficient depth to 
clear the projection of the second reinforce 
rings. 
The vent fields are ^th of the breech and 
first reinforce. 
The chase girdles are J^th part of the 
chase. 
The length of the muzzle is equal to the 
diameter of the second reinforce ring in 
heavy guns ; and in medium guns ith of the 
length of the piece. The diameter of the 
swell of the muzzle is equal to the diameters 
of the second reinforce rings. 
The bottom of the bores of heavy brass 
guns is a plain surface, meeting the sides in 
a small arc described with a radius of J^th of 
a calibre : in medium and light guns they 
are hemispherical, and their vents form an 
angle of 75 degrees with the axis of the 
piece : making in light guns |rd of the cali- 
bre, and in medium Jth of the calibre, from 
the extremity of the bore. 
The vents of heavy guns are a fifth of an 
inch in diameter. 
In medium and light guns there is a por- 
tion of metal beneath the neck of the cas- 
cable, for receiving the loop of the elevating 
screw. The lower part of it is the arc of a 
circle, described with a radius equal to the 
semidiameter of the neck: the position of 
the centre is rth part of the distance from 
the extremity of the breech moulding to 
that of the button, and is ^th of the diame- 
ter of the neck below it. 
Medium and heavy guns are cast with 
dolphins, by which they are occasionally 
suspended, and they consequently should be 
placed over the centre of gravityyof them, 
or rather, so that the breech may preponde- 
rate in a small degree. % 
/ 
Bb 
VOL, I. 
