THE ROYAL ARTILLERY INSTITUTION. 
57 
a practicable breach will not be produced. If the strikeable surface 
is too small only slight results can, in general, be expected. Thus, 
in demolition fire too, all the circumstances of the case have to be 
taken into consideration. If we are not tied down to a particular 
distance we can the better take into account the object to be attained 
and the nature of the target in fixing the charge and elevation. In 
doing this it should always be remembered that heavy charges (by 
giving a high final velocity) are the most advantageous, because the 
projectiles then penetrate deeper and the bursting effect is greater. 
Since, in the case of demolition fire, the effect does not depend on 
the cutting out of a fixed line, it can be undertaken at greater dis¬ 
tances if the strikeable surface is large enough. It can even occa¬ 
sionally be carried on by the batteries of the first period; because it 
is important to destroy, as soon as possible, the defensible barracks, 
flanking batteries, and, in general, secure shelter of every kind. 
6. Choice op the Point op Impact in Enfilade Fire. 
The process of arming the works and placing them in a state of 
defence has, in general, to be hindered by means of enfilade fire from 
the batteries of the first period, established at considerable distances 
from the objects of fire. In this case the full service charge can, as a 
rule, be employed; the trajectory, owing to the long range, possessing 
already sufficient curvature. 
Reduced charges are only to be employed when a protecting obstacle 
has to be fired over to hit a fixed point behind it. To do this the 
angle of descent must be calculated, according to the given conditions ; 
and, in the case of horizontal objects of fire, for the nearest point of 
impact, just as with vertical objects the lowest point is taken. 
In enfilading a terreplein unprovided with traverses the greatest 
number of hits will be obtained by taking the nearest point of impact 
as close as possible to the protecting crest. On the other hand, the 
necessity of employing the heaviest allowable charges debars the 
nearest point of impact from being taken too close to it. 
The charge and elevation are determined for the point of impact 
already decided on, and the trajectory then sufficiently raised, by in¬ 
creasing the elevation in proportion to the range, to bring the mean 
point of impact to half-way between the nearest point of impact and 
the end of the terreplein. If, therefore, what has to be done is to 
bombard the interior of a work, and if there is no occasion to direct 
the fire in preference against any particular portion of it, the mean 
point of impact should be so selected that the hits may be uniformly 
distributed, and that, as regards the longitudinal and lateral spread of 
the projectiles, as many shots as possible may be utilised. 
If the objects of fire have a considerable extent of surface, we should, 
both when enfilading lines unfurnished with traverses and when bom¬ 
barding the interior of a work, direct each gun against a fixed 
point, so as to bring every part of the work under an equal amount of 
fire. Since the lateral spread of the projectiles is considerably less 
