“In a three-decker might be witnessed the extreme phase of the evil: long 32-pounders, 18-pounders, and carronades, requiring three sizes of shot and four classes of full charge, with as many reduces as caprice might suggest. All this variety of supply was to be distinguished and selected in the magazines and shot-lockers—circulated with perfect exactness in the confusion and obscurity of the lower passages, to a particular hatchway, then up to the deck where was placed the gun for which each charge or shot was designed: and this was to be accomplished, not with the composure, deliberation, and attention that the nature of the operation itself demanded, but amid all the excitement and hot haste of battle.”[108]
The plans of M. Paixhans, in particular those for the adoption of shell fire on a large scale, were viewed with much misgiving in this country. But, as already noted, Great Britain moved very cautiously in the counter-measures which she took in view of the policy then under review in France. It is probable that the publication, in 1828, of a memoir by Captain F. A. Hastings, R.N., commanding the Greek steam vessel of war Karteria, had great effect in encouraging the authorities to countenance shell fire. From this memoir it appears that Captain Hastings was led, by arguments similar to those which influenced M. Paixhans, to consider the possibilities of discharging at an enemy something more devastating in effect than the solid sphere of iron in general use. His navy was inferior in numbers to possible rivals; he expressed the opinion that this inferiority might be nullified by the use of shell, but he “got well laughed at for his pains.” Soon afterwards, however, he came across Paixhans’ work. Acting on his ideas, he applied shell fire with great success in action, and at once became an enthusiastic advocate of the new arm. One great objection to its adoption he almost laid to rest: the increased danger due to the carriage of shells. He denied that there was any increased danger. On the contrary, he considered charged shells less dangerous than powder in cartridges, if properly packed. They were less dangerous, he argued, because their use involved bigger and therefore fewer guns than an ordinary ship would carry. Therefore there was less confusion in action, less jostling, more working spaces, and fewer cartridges and projectiles to be handled. In support of his opinion he could point to an entire absence of accidents during his commission in the Karteria.
In 1829 a general increase of calibre was obtained by the inexpensive expedient of boring out guns to their next larger calibre; in which operation the opportunity was taken to arrange for a reduced allowance of windage for the guns thus altered, and thus to secure a double gain, of increased calibre and improved discharge. Experiments were made with shell fire à la Paixhans. Tentative designs of shell gun were produced by the ordnance department, and guns of 8-inch, 10-inch and 12-inch calibre were made; one of which, an 8-inch, mounted in H.M.S. Phœnix, made very effective shooting at San Sebastian in the year ’36 and gave thereby an advertisement to shell fire.
And then, in 1837, came the French decision to adopt a shell gun armament generally.
The result was a complete and corresponding reorganization of British ship armament.[109] By 1839, the authorities being at last convinced of the necessity of meeting the French innovations with similar innovations on our part, Colonel Munro’s proposal of 1825 had been adopted, and various classes of ship were equipped with six different patterns of 32-pounder long gun. With these were associated, in small numbers, 8-inch shell guns of fifty-three and sixty-five hundredweight. Thus this country by a single move countered the two moves made by France in ’29 and ’37 respectively, and denied to M. Paixhans, for a while at any rate, any considerable change in the relative strength of the two navies. As in the French navy, shell fire was only introduced as an auxiliary to the solid shot. Thus the great ideal of unity-of-calibre, so long sought and at last almost attained, was found incompatible with the other ideal, shell fire; and was therefore sacrificed. No doubt was felt, at this time, as to the necessity for two types of gun. The superior power of shells was dreaded, suspected, half-acknowledged; but the superior range and penetration of solid shot fired from long guns made the latter indispensable to ships’ equipment. So shell and large-bore shot guns were mounted in ships side by side. Old guns and carronades were “scrapped” in large numbers to give place to the new ordnance; and an official announcement was made, in justification of the Admiralty policy, that “the changes were not made until they had been adopted by foreign powers.”
§
Shell fire was at last accepted. The perils associated with the carriage of shells in wooden ships were found to have been exaggerated; experience soon confirmed that, if special precautions were taken, no danger was inherent in their use.
Even after its introduction into our fleets the shell gun was regarded by many as of doubtful value. For some years previously the opponents of shells had agitated the question of a compromise: viz. the use of hollow shot uncharged, instead of solid balls. And when M. Paixhans had published his great scheme they had held that more advantages would have been offered by it if he had stopped short at charging the shot with powder, and had advocated merely hollow shot, which by their larger size would give the advantages of heavier calibre. But the argument for hollow shot was finally demolished in 1837 by a writer whose views carried great influence. Incorrectly attributing to M. Paixhans himself the proposal to use them, Captain Simmons, R.A. proved clearly and conclusively their comparative uselessness. The adoption of hollow shot, he showed,[110] would be tantamount to a reversion to the use of stone or granite projectiles; it mattered little, for practical purposes, what the projectile be formed of, so that its density be what was desired: whether hollow iron or solid granite. Except the Turks, who still guarded the Dardanelles with granite-firing cannon, all nations had abandoned granite in favour of the heaviest metals, and no one questioned the vast improvement thereby obtained, “except the inventors of the carronade and the promoters of this same system, improved by M. Paixhans.” As a matter of fact the carronade was designed for the special circumstances in which hollow shot were not without value. And M. Paixhans, as we know, never intended to forego the use of a charge of powder in the cavity of his boulet creux. But the arguments of Simmons sufficed to kill the advocacy of hollow, uncharged shot.
Doubt was cast, too, on the capacity of the shell gun to project its shells to a sufficient range and with sufficient striking velocity in action. In the case of the first shell guns cast, a strict limitation had to be placed on the powder-charges which could safely be used; and this involved a limitation of range, apart from the reduction due to the lower specific gravity of the projectile. Both French and English shell guns suffered in this respect. For this reason they had been deemed by the French specially suited for use in steam vessels, which could by their locomotive power attain the desired range. But, it was said, steam gives the power of avoiding, as well as of closing to action; and steam, it was foreseen, was a giant which would one day haul even ships-of-the-line into position for battle. Might not future actions be fought at considerable ranges? And for close-quarter work, could not our powerful long guns, double-shotted, be used with greater effect than shell guns?
Then, again, the flight of shells was not nearly so certain as that of solid shot. The effects of eccentricity, which in the case of solid shot had always militated against accurate shooting, were in the case of shells considerably enhanced. The varying thickness of the shell, the lack of homogeneity of the metal, the presence of the protruding fuze, all tended to produce eccentricity and give a bias. The centre of gravity of a shell was seldom at its centre of figure; and this eccentricity was the cause of deviations in flight, in range and direction, which made the trajectory of a shell not easily predictable. Savants and artillerists, both here and in other countries, discussed for years these deviations, and on the relationship between range and eccentricity numbers of trials were made and theories were propounded. Which is the more strange, seeing that Robins had placed on record an almost complete solution. Briefly, the effect of eccentricity may be explained as follows. Just as a stick held vertically by a thread receives, when struck at a point in it other than the centre of percussion, a tendency to motion not only of translation but also of rotation round that centre of percussion; so a spherical shell whose centre of gravity lies away from its centre of figure receives, from the pressure of the powder gases acting at its centre of figure, a rotary motion about its centre of gravity in addition to a motion along the bore. If the centre of gravity lies below the centre of figure this rotary motion is in such a direction that, as the shell approaches the muzzle, points on its upper surface are moving towards the muzzle, points on the lower part are moving inwards. And this rotation, maintained during flight, has the effect—as was demonstrated by Robins with the musket ball—of giving the sphere a vertical deviation in a downward direction; i.e. of reducing its range.