THE EOYAL AETILLEEY INSTITUTION. 
147 
weakness, and any means by which either of them can be reduced will not fail to 
be beneficial. 
“ The relief which a heavy mass affords in receiving and absorbing the force of 
a blow, admits of many familiar illustrations. The different feelings with which a 
heavy or a light stone may be struck when held in the hand are well known, but 
perhaps the most singular instance of this law may be found in a case which 
excited much wonder in the last generation—namely, that of a man who was accus¬ 
tomed to exhibit himself sustaining a very heavy stone on his chest while lying on 
the floor. Several large sledge-hammers were freely used upon the stone, but 
although so much force was applied, there was no injurious effect upon him who 
submitted to such an ordeal. The relief afforded by simple weight in these 
examples gives just the same immunity to a gun. Such a conclusion would lead 
to the inference that the greatest durability will be associated with the heaviest 
breech, and the following examples will prove this deduction to be well founded.” 
Mr. Bigg gives illustrations of various guns in support of this idea, 
and mentions specially that at the siege of Charleston— 
“One gun, a 30-pr., showed most extraordinary and unique powers of endurance. 
Through some accident in its construction, the wrought-iron reinforce was shrunk 
firmly on the breech, and not on the body of the gun; consequently its weight and 
inertia became available to resist the first impact of the discharge; the longitudinal 
strain was thereby diminished, and the gun relieved from much of its usual 
load. 
“After firing 4606 rounds, this gun burst into seven pieces.” .... 
Mr. Bigg also quotes from Major Palliser as follows, page 11 *— 
“ The same idea lurks in the following remarks by Major Palliser, although the 
last sentences contain the gist of the whole argument:— c There are two ways in 
which a gun can burst—viz., by the bursting of the barrel, or by the end being 
blown off. In an ordinary cast-iron gun, the whole longitudinal pressure acts on 
the end of the bore. If the bore be 8 ins. diameter, this pressure will, in round 
numbers, be distributed upon 50 square inches. If, however, the gun be bored up 
to 13 ins. and lined with a barrel 2^ ins. thick, the longitudinal pressure will act 
upon 50 square inches, as before, but will be transferred to a surface of about 
130 square inches, and thus the longitudinal strength of the gun becomes more 
than doubled. In fact, every way of regarding the subject shows that the circum¬ 
ferential strength should be applied internally, and the longitudinal strength should 
be borne by the outside; and this is precisely the reverse of the principle upon 
which the wrought-iron guns of the service are made.’ ” 
Mr. Bigg adds 
“ The idea of separating the forces into circumferential and into longitudinal is 
very correct in theory, and practical, as well as the assignment of a special share of 
duty to each part of the gun. . . . * 
“ In conclusion, it is evident that there can be no reason why English guns shall 
not always reliably exhibit the same endurance that was shown by the solitary 
Parrott gun that bore 4606 rounds. It is simply a question of correct principles of 
construction, and if it be desired still further to enhance the powers of the guns 
which Major Palliser has begun so well, the question of longitudinal strain is that 
to which attention must be given.” 
These remarks by Mr. Bigg are very valuable, and it is to this 
very question of longitudinal strain that my proposition is mainly 
