28 
MINUTES OF PROCEEDINGS OF 
There is no such thing as point llanh range , and this term which has no 
equivalent in Trench, should if possible be disused, or its conventional 
meaning be very carefully guarded. What is usually called point 
blank range, viz. the distance at which a shot impinges on a level plane 
when fired parallel with it, is really the range due to an angle of elevation 
equal to the angle subtended by the height of the gun from the point struck. 
The portee de but en blanc of the Trench is what we term the line of metal 
range , referred however not to the plane, but to the second intersection of 
the. trajectory with the line of sight. 
6. Point Blank. —A gun is only laid point blank when the axis prolonged 
passes through the object aimed at. The term had its origin in the erro¬ 
neous notion of the gunners before Bobins that every shot travelled a certain, 
and indeed a considerable distance, in a right line before it was acted upon 
by gravity, and to them point blank range expressed a definite although 
imaginary distance. The use of the term at present is productive of much 
confusion. 
“ Shooting Point Blank is when your mark you Shott at may be reacht in 
a Direct line without Curvity. A peice may be Elevated and yet shoot 
blank. Tor two peices on one and the same Battery being both within Blank 
the one may be layd level the other may Elevated so as to batter the same 
Tortificacation only some part that is higher. Therefore a peice may be 
Elevated and yet shoot Point Blank. But it must be within the right line 
of the peices reach/ - ’— Cocker’s Gunnery (MS. War Office, 1710). 
7. Terminal Angle. — Angle de chute. The angle which a tangent to 
the trajectory forms with the horizontal plane at the point of descent. 
8. Angle of Incidence.— Angle d’incidence. The angle which the 
tangent to the trajectory makes with the actual surface at the point of 
descent. 
9. Angle of Descent. — Angle d’arrivee , The angle which the tangent 
to the trajectory makes with the horizon at the height of the crest of the 
parapet, or other object to be cleared. It is rather less than the terminal 
angle. 
10. Height of the Object. —Distance of the point intended to be 
struck above or below the horizontal plane passing through the mouth of 
the piece. Thus, if the height of the muzzle of the gun above the zero 
plane, is 17 ft., and the point intended to be struck is the centre of a 
9 ft. target on the plane, the height of the object will be minus 12J ft. 
11. Elevation of the Object. —Angle which a straight line drawn 
from the object to the centre of the mouth of the piece makes with the true 
horizon. 
12. Line of Metal.— Ligne de mire naturelle. Bight line connecting 
the front and back sight when the latter is at its lowest point, i.e. connecting 
the notch on the tangent sight with the notch on the swell of the muzzle or 
dispart sight, in smooth-bored guns, connecting the tangent and trunnion 
sight, or the ratchet and dispart sight in Armstrong guns. 
13. Line of Sight.— Ligne de mire artificielle. —Bight line from the 
extremity of the tangent scale, at whatever elevation, to the front sight what¬ 
ever it is. When this line is directed on the object it becomes the line 
from which angle of elevation of the axis (1) is measured. 
