MEPPEN EXPERIMENTS. 
275 
diameter of the chamber of the 71-ton gun is 17*32 ins., that of the 
80 and 100-ton guns being 18*0 and 19*7 ins. respectively, that is to 
say, it is 1*57 ins. greater than that of bore as compared with 2*0 ins. 
increase in the 80, and 1*98 ins. in the 100-ton gun. 
Speaking generally, then, the bore of Krupp's gun is relatively 
rather longer, and the chamber less enlarged than in the 100-ton gun, 
while in the 80-ton gun the bore is actually the shortest, and the 
enlargement of the chamber actually the greatest of the three. 
It should be understood that our own investigations have led to the 
adoption of far greater length of bore than is exhibited in any of 
these three guns. I am informed that a B.L. gun of 40 tons, 26 calibres 
long, is in course of construction. I am speaking, therefore, of the 
71-ton gun which was made last, simply as having actually embodied 
in it a further stage of progress than the 80-ton gun. The first gun 
with an enlarged chamber, that I know of, was a field gun fired by 
Sir J. Whitworth at Southport in October, 1872. 
On the proportions of bore and chamber mainly depend the power 
of the guns. To be able to make a comparison between them, 
discrimination is necessary. It would not be right to take equal or 
proportionate charges as the basis of the comparison, because the 
principle on which a long gun is advocated is that any greater result 
can thus be got from a gun with a given strain on it, but at the expense 
of some waste of powder. 
It is clear, then, that looking to the endurance of the gun rather 
than the expenditure of powder, the basis of comparison should be 
proportionate pressures. It would scarcely be right to say equal pressures, 
because the thicker gun can fairly be expected to bear a greater strain 
than the thinner one. Now, the best results obtained from these three 
guns are as follows :— 
The 80-ton gun at Woolwich with a proof-charge of 445 lb., giving 
a pressure of 21*5 tons, discharged a projectile weighing 1728 lbs., 
with a velocity of 1658 f.s.—having 32,938 ft. tons stored-up work, or 
658*57 ft. tons per inch circumference—equivalent to a penetration of 
a 32*34-in. plate of wrought-iron. The 71-ton gun at Meppen is 
reported, on one occasion, with a charge of 485*1 lbs., giving a pressure 
on the gun of 20*92 tons, to have discharged a projectile weighing 
1715 lbs., with a velocity of 1703 f.s.,—having therefore 34,489 ft. tons 
stored-up work, or 697*02 ft. tons per in. circumference—equivalent to 
the penetration of a plate 33*5 ins. thick. 
During the public trials in August, the 71-ton gun was not tested 
so severely, and it is therefore right to class the above in the same 
category as the Woolwich proof-round above mentioned. In August 
the average weight of the chilled projectiles was 1712*6 lbs. The 
firing charge was 452 lbs., the initial velocity was 1648 ft., the stored- 
up work 32,241 ft. tons—the work per inch circumference 651*59 
ft. tons, equivalent to a penetration of 32*12 ins. The pressure on 
the bore was 19*85 tons. 
The highest result obtained with the 100-ton gun of 17*72 ins. 
calibre, hitherto, has recently been furnished me by Captain Noble; 
it is as follows ;—charge, 573 lbs.; projectile, probably about 2,000 lbs. j 
