THE ROYAL ARTILLERY INSTITUTION. 
397 
No. 4. 12-pr. Armstrong. 
Weight of Carriage, Gun, &c., Stationary. 35-5 cwt. 
„ „ Moving. 53*2 „ 
Increase 17‘7 =50 per cent. 
No. 5. 10 “inch Mortar. 
Weight of Mortar, Carriage, &c., Stationary ... 63-5 cwt. 
Moving. 93*2 „ 
Increase . 29*7=46 per cent. 
The high rate of increase obtained with the 10-inch mortar, as compared 
with those of the 18-pr. and 20-pr., was thought to be due to the 
low wheels (4 ft. 2 in. diameter), to prove w r hich the same 20-pr. as used in 
No. 3 Experiment was mounted upon the mortar carriage wheels with the 
following result:— 
Weight Stationary. 44-75 cwt. 
„ Moving. 75-75 
Increase . 31-00=70 per cent. 
In all the experiments the greatest elevation of the indicator took place 
just as the carriage wheels got fairly on the bridge, and when the horses and 
limber had left it; and in no case did the horses affect the indicator except 
in that of the 12-pr. when it was just raised through a fraction of the first 
space, but was greatly exceeded when the carriage came on. Small, how¬ 
ever, as the effect thus produced by the horses really was, it is probable that 
it helped to create the high rate of increase as shewn by the 12-pr. carriage 
between whose weight and that of the horses there is not so great a 
difference as exists in the other carriages. 
