68 A CALCULATION OF PROBABILITY OF FIRE. 
It will be observed that for the 6” gun, Marks IV. and VI, charge 
48 lbs., E.X.E. MV 1960 fis., the probable rectangle as given in the 
handbook for 1891 is nearly as large at 100 yards as at 5000, and the 
50 per cent. length zone is larger, viz. 30 yards at 100 and 29 yards at 
5000; in other words, the gun according to this range table is more 
accurate at 5000 yards than at 100—its accuracy would appear to 
increase from 100 up to 3200 yards and then to decrease. This accounts 
for the apparently paradoxical result that you would get a greater 
percentage of hits at 2000 than at 1000 yards. 
At 3000 yards the 50 per cent. zone is still less than at 2000, 
ie. the gun is more accurate, but at this range the horizontal equivalent 
value of the target presented by the objective is considerably less, 
consequently the percentages begin to fall off. 
