444 
MINUTES OF PROCEEDINGS OF 
Column 3.—The figures in this column are obtained by plotting the 
deflections at five ranges, deflection being taken as ordinate and range as 
abscissa, striking a curve and reading off intermediate deflections. 
Column 4.—If we take the difference between two adjacent heights 
on the tangent-sight bar from column 2, say 18*2 — 164 = 1*8 tenths 
of inch, and the difference of the corresponding ranges from column 1 , 
that is 700 — 642 = 58 yds., we get the proportion 
t. t. yds. 
1-8 : 1 :: 58 : a? = 32 yds. 
Column 5.—To find the deflection of the projectile due to 0*1" on 
the deflection scale, we have the proportion 
yds. 
35*9' 7 : 0-1" :: 700 x 3 : ^ = 5*9ft. 
Column 7.—The angles of incidence in this table seem to have been 
calculated from the height on the target of the mean point of impact 
and the distance behind the target of the mean range from 
tan 6 = 
a {A — a) ’ 
where 6 is the angle of incidence, h' the height above the plane of the 
mean point of impact, A the range up to the graze of the projectile, 
a the distance of the target from the gun. Five such angles being 
calculated and taken as abscissae, the ranges being taken as ordinates, and 
the points obtained being joined by a continuous curve, the intermediate 
angles for intermediate ranges can be read off by inspection. The 
angles in this column are slightly less than those obtainable by calcula¬ 
tion from the ordinary formula. 
Column 8.—The figures in this column are obtained from a table of 
natural tangents. 
The following extracts from similar tables will be of use further on 
in working out an example. 
B. 
O s 
rd 
to d 
M 
O H 
•J3 « 
be 
§ S' 
s ° • 
c3 © 
"rS 
d 
S °.S 
3$ -g 
03 5 S3 
f-< R <D 
r O rtf 
a <3 
Hi o 
r 2 + 
S C 
'c 
fcUCTS 
'o 
4s 
o 
Hi a 
11 
i's 
EH ® 
be 
a 
yds. 
1225 
1225 
tenths 
of in. 
39-1 
44-4 
tenths 
of in. 
1-8 
2-0 
yds. 
ft. 
Charge, T9 lbs. 
26-8 
10-2 
6 13 
Charge, 1*7 lbs. 
23-3 I 102 7 3 
6 65 
7 54 
0-1213 
0-1388 
