224 
THE VALUE OF A HIGH SITE FOR COAST ARTILLERY. 
Let e and e', as before, be the ‘ overs * which would just cause the 
objective to be missed, from the low and high site, respectively; and let 
E' be the ‘ over ’ which would result from the same mistake, if made on 
the high site, as that which caused e on the low. 
Then 
and 
6 = 13 + 2 = 15, 
e'=ll*7 + 2 = 13*7, 
15 
1-08 
= 13-88. 
Hence as E' is > e', the same mistake is more disastrous on the site of 
100' than on the level, when - = 2. 
a 
Next let there be an objective, as in fig. 8, where a is represented 
by 1 and b by 4*5. 
Fig. 8. 
Here 
and 
6=13+4-5 = 17-5, 
e'=11*7+4*5 = 16-2, 
E '=m - 16 ' 2 - 
Hence as E' is equal to e', the same mistake will have the same 
effect from either site, when - = 4*5. 
a 
It is at once seen that as the ratio - increases, the advantage of the 
high site will also increase; so that on the whole, mistakes of class B 
have less effect on the high site than on the level. 
V. Mistakes with Tangent Elevation. 
Tangent elevation does not alter with the height of the gun and the 
line of sight always passes through the object aimed at. It will there¬ 
fore not be necessary to investigate the mistakes, classed as A and B, 
separately. We will therefore consider all mistakes, accidents etc. as 
causing a certain wrong elevation to be given to the gun. 
