THE ROYAL ARTILLERY INSTITUTION. 
19 
TABLE I. 
MEAN RANGES OBTAINED IN 40-pr. PRACTICE UNDER THE FOLLOWING 
CONDITIONS. 
(a) Gun on a travelling carriage; axis 4J ft* above tbe plane; ele¬ 
vation given by tangent scale above a mark 4^ ft. above the plane, which 
is nearly a dead level. 
(b) Gun on a naval carriage; axis 8 ft. above the plane; elevation 
given by tangent scale above a mark 8 ft. above the plane. 
(c) Gun on a garrison sliding carriage; axis Yl\ ffc. above the plane; 
elevation given by spirit-level. 
Observed mean Ranges . 
Nominal 
elevation. 
(a) 
4£ft. 
(*) 
8 ft. 
(*) 
17| ft. 
0° 
312 y 
376 y 
492 y 
l q 
682 
723 
783 
2° 
1061 
1077 
1151 
3° 
1429 
1448 
1491 
4 Q 
1779 
1806 
1873 
5° 
2116 
2129 
2274 
6 ° 
— 
2563 
— 
7° 
2727 
2925 
2955 
8 Q 
— 
3186 
— 
9° 
3303 
3562 
3454 
10° 
3377 
3751 
— 
The above are the means of solid shot, common shells and segment shells, 
because we recognize no difference in the range of those projectiles, nor is 
there in fact, practically, any sensible difference. It is evident that unless 
we are prepared to promulgate different Tables for every sort of service, these 
results must be harmonized into some general Table which shall be true for 
the gun, however it is situated relatively to the object to be struck. This 
is fortunately very easy. 
4. Let h — height of the axis of the gun above the plane, 
a — distance of the mark above which the elevations are given, 
b = the height of that mark above the plane, 
R = the horizontal range recorded, 
6 — elevation by tangent sight above the mark b, 
6 ± = the true angle to which the range R is to be referred. 
(1) Then let us first suppose the case of the gun laid at the given 
object b for direction ; but the elevation given by spirit-level. In this case 
the height of the object b is immaterial, the angle recorded namely RGE of 
