274 
MEPPEN EXPERIMENTS. 
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1.1 1' L I I L 
SCfiLE OF rEET 
DIAGRAM 3 
the charge, which has been attributed to the prismatic powder em¬ 
ployed. But while the regularity of the powder is a necessary element 
in such a result, I cannot see how it alone explains it. The effect of 
variation in powder doubtless would be seen in the deviation of the 
shot in the vertical direction only, but it appears to me that bad 
shooting from the faults in the bore of the piece would be seen in 
irregularity both in the vertical and horizontal direction. If the 
vertical deviation is very small, then it argues not only that the powder 
was regular but that the bore also carried true to within the limit 
exhibited, and a cause for the error in the horizontal direction must be 
sought elsewhere. With regard to the powder, it stands to reason that 
a charge composed of a fixed number of prisms of uniform size and 
density gives promise of greater uniformity being attainable than when 
pebbles are employed; and there seems no reason to doubt that 
whatever difficulties were at first experienced this has been achieved. 
Surely if two attempts are made to obtain regularity in powder—one 
by employing prisms each uniform in size and shape, and if possible 
pressed uniformly, and another by means of pebbles of a accidental 
shape from uniformly pressed powder cakes—the former, though it 
may be difficult, offers promise of ultimate success in the higher degree. 
As to the windage, stress can hardly be laid on the great reduction in 
the case of the common shell; the two kinds of projectiles made 
pretty nearly equally good practice. Lastly, as to the proportions of the 
bore and chamber. The most striking feature is the length of the bore. 
Figs. 2, 3, and 4 show the relative lengths of the best heavy guns at 
present in existence, by which it appears that the bore of the 71-ton 
gun is only 20 ins. shorter than that of the 100-ton gun, and 55 ins. 
longer than that of the 80-ton gun. The chamber in length is 60*6 ins., 
that of the 100-ton gun being 59*7, and of the 80-ton gun 59'6. The 
calibre of the 71-ton gun is 15*75 against 16 in the 80, and 17*72 in 
the 100-ton gun. Consequently, the bore of the 71-ton gun is 21*8 
calibres long against 18 in the 80, end 20*5 in the 100-ton gun. The 
