THE EOYAL AETILLEEY INSTITUTION. 
203 
The experiment was made as follows :— 
A paper tube 0'5-inch in diameter was fixed in the bottom of a 27*5 lbs. 
cartridge, 18 lbs. of powder were then put in and the tube closed with a 
piece of calico, and about a dram of fine grain powder put in as priming. 
The remaining 9J lbs. were then added, and the gun loaded with this 
cartridge and a 110-lb. shot. The priming was then fired by means of a 
magnetic tube, the wires from which passed out through the vent piece. 
By this mode of lighting, a very large surface of the charge was acted 
on, and the initial development of gas much increased; the total initial 
strain on the gun was, therefore, more severe than if the cartridge had been 
lighted at the end, but this strain was more equally divided, it did not take 
place as formerly, chiefly in the shot chamber, but was spread over the powder 
chamber, and acted with considerably increased force against the breech of 
the gun, which in muzzle-loading guns is the strongest part, and in breech¬ 
loaders the .weakest.* 
11. No further experiment on this subject seems to have been carried 
on up to the date of General Lefroy's memorandum. 
In consequence of his recommendation, the Committee decided to institute 
a course of experiments for the purpose of determining the effect on the 
velocity of the projectile, due to igniting the cartridge in different positions. 
The gun employed for this purpose was a 'bronze one of 122 cwt., which 
was cast as a block in the Royal Gun Factories in 1860, and was of the 
outside dimensions of a 68-pr.; vide tracing. It was bored to the calibre 
of a 42-pr«, viz. 6*9 inches, and was fired with a charge of 14 lbs., and 
cast-iron solid shot weighing about 41 lbs. 
The first series was for the purpose of determining the velocity of the 
projectile when the cartridge was ignited in six different positions, com¬ 
mencing from the rear, the powder being common service L.G. 
The vents were bored as follows :•— 
No. 1. So that point of ignition should be exactly at the base of the charge. 
No. 2. Half-way between No. 1 and the service vent, or No. 3. 
No. 3. The service vent. 
No. 4, 5, and 6. At the respective distances of 1*38, 2'76, and 4*25 inches 
in front of the true vent, or No. 3, that is about 1*4 inches apart, 
The several positions of the vents are shown in the tracing above-men¬ 
tioned ; each vent was opened as required, all the others being closed by a 
screw plug, which admitted of removal. 
In this manner five consecutive rounds were fired with each vent, and the 
velocity of the projectile observed. 
The experiment was completed in one day, and every round was fired 
under the same circumstances. 
The following table gives the results. 
* Lately Mr Whitworth, appears to have adopted this method of igniting in the centre by means 
of a tube in the cartridges for Ms 70-pr. gun, tried by the Armstrong and Tf hitworth Committee. 
[VOL, Y.] 27 
