THE ROYAL ARTILLERY INSTITUTION. 
49 
right face of Lunette No. 53 which had to be breached. This was so 
much the more unfavourable because at the distance of 750 metres 
only a small charge could be used. The masonry consisted of red 
sandstone, and had a thickness of 1*25 metres at the top and 
1-90 metres at the base. By making use of a mine-gallery the effect 
could be very closely observed, and it proved that a great number of 
the projectiles glanced off on striking the intact masonry. Not till 
after four days ; firing, during which a thousand projectiles were 
expended, was a practicable breach produced.* 
When a high angle of descent is combined with a small angle of 
impact it is all the more unfavourable for the penetration of the 
projectile. 
With the object at a given distance, and with given profiles, the 
requisite curvature of the trajectory can only be obtained by modifying 
the charge of powder. Should we, however, owing to the nature of 
the ground and the disposition of the siege works, not be tied down to a 
fixed distance, the necessary angle of descent may often be obtained by 
increasing the distance, even when using heavier charges. In the latter 
case we should also obtain greater final velocities within that distance 
at which, in general, curved breaching fire might be attempted with a 
prospect of success. If, therefore, the greater distance admits of the 
employment of heavier charges, we should give this combination the 
preference, provided we do not thereby sacrifice to any great extent the 
probability of hitting, and provided the power of resistance of the scarp 
to be breached appears to render desirable a greater final velocity. 
With horizontal objects of fire (as in enfilading), it must be borne in 
mind that though the longitudinal spread ( Langenstreuung ) increases 
very nearly in proportion to the distance, still with all charges it is 
nearly equal for equal ranges. Should, therefore, in the case of terre- 
pleins insufficiently provided with traverses, the objects of fire be of 
sufficient longitudinal extent, an increase to the distance, by allowing 
of the employment of large charges, will be an advantage in enfilading. 
With lines well furnished with traverses it is different; and in this 
case it is not allowable to fix on a greater distance unless the minimum 
charge fails to give the requisite angle of descent. 
With smooth-bore guns curved fire was only used for ricochet 
purposes, and curved breaching and demolition fire was -only employed 
incidentally on real service (Alessandria, 1799, and Hiiningen, 1814). 
Both in England and Prussia experiments on the subject were 
carried out, but the Austrian artillery had paid no attention whatever 
to the last-named kind of fire. As, however, by the introduction of 
breech-loading rifled guns, curved breaching fire attained increased 
importance, similar experiments were undertaken in Austria in the 
year 1861 at Bothenneusiedel, and in 1862 at Verona, and have since 
then been practised to a large extent by the artillery against fixed 
objects. The Prussian artillery, by the experiments at Schweidnitz 
in 1857, at Jiilich in 1860, and again at Stettin and Silberberg in 
* Decker, Mittheilungen liber die Anwendung des indirecten Sckusses, &c, 
