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Appendix No. 4.
SINGAPORE.
Fire from Mount Siloso Battery.
Two weak points.
Considerations of western defences.
Amount of metal thrown by Mount Siloso Battery, and effect on single cruizer.
Advantage of position.
Attack by wooden squadron.
Attack by iron clads.
North-west silencing position,
gun of Mount Palmer Battery, and have arrived at the extreme lateral range of the three right-hand guns of Blakang Mati East Battery, after which she would be still exposed to the fire of four 7-inch guns and two 64-pounders.
36. At the western entrance of the harbour the position is of a much simpler character. A narrow entrance is defended by a single battery and a few submarine mines. The channel of approach from the Cyrene Shoal is swept by the fire of two 7-inch guns and the two 64-pounders, and, in the case of vessels coming south of a line joining the point "A" (see chart*) with the battery, the third 7-inch gun on the left of the battery comes into play. The 64-pounders being mounted on "C" racers in emplace- ments of suitable design, they can be brought to flank the front of Blakang Mati (from which Mount Siloso stands out as a sort of natural bastion), and can also bring a reserve fire to bear on the harbour itself.
III.
37. The two points which will strike an observer are: (1) that a very small weight of metal is opposed to an enemy's guns; and (2) that the works derive no support from collateral works, or, in other words, that the amount of artillery did not allow of its being distributed in such a manner that a concentrated fire could be obtained from each individual position.
38. As I have just been considering the purposes which Mount Siloso Battery fulfils, it will be convenient to examine the weakness of the western defences before taking up the question of the eastern defences. Whilst discussing in what respect each battery is defective, as regards the general question of defence seaward, I will remark on the points which militate against the self inherent defensive qualities of the works, as well as upon the absence of those fortificational requirements and conveniences which could not be provided by virtue of the nature of the isolated positions, and for want of funds not available out of the limited vote.
39. As stated on the last page, the greatest amount of fire to which a vessel approaching in a fair channel would be exposed is that from two 7-inch guns and two 64-pounders. Taking the interval between the rounds as one minute, the pieces having to be carefully laid each round, we see that guns weighing in all about 191⁄2 tons will throw about 3 cwt. of metal per minute, so that in the fifteen minutes which a vessel, steaming cautiously at 6 knots, would take to approach over 3,000 yards, she would be exposed to the fire of 24 tons of projectiles, representing sixty rounds. Supposing a passage cleared through the submarine mines and a vessel approaching at the speed indicated, with the intention of running the gauntlet, she would receive this fire chiefly end on; she would not be able to reply to it; and for the last 1,000 yards, her decks would be exposed to a plunging fire. Assuming that 25 per cent. only of the rounds took effect (which is certainly a minimum considering the position of the battery) she would be crippled, and probably on fire long before she reached the entrance of the harbour.
40. Again, the height of the work above the sea, together with the fact that the cliff in front will catch all projectiles falling short, gives the guns an advantage over many times the same weight of metal carried on shipboard. Thus we find that, at Sebastopol, the Telegraph Battery, mounting the same number of guns as Mount Siloso Battery, and constructed on a cliff about 100 feet high, beat off four of our men-of-war with heavy loss, two of the ships being disabled, whilst it suffered no loss itself either in men or guns.
41. Supposing that the small squadron of wooden vessels referred to at p. 243 wished to silence the guns bearing on the area of approach, and let the ships be armed with probable equivalent English guns as follows:-
One corvette: two 7-inch muzzle-loading rifled guns of 63 tons; ten 64-pounders of 64 cwt. Two clippers each: two 7-inch muzzle-loading rifled guns of 6 tons; six 64-pounders of 64 cwt. Three gun-vessels each: one 7-inch muzzle-loading rifled gun of 63 tons; three 40-pounder breech- loading rifled guns of 55 cwt.
A salvo from all these guns would throw a mass of metal weighing 2,683 lbs., or, allowing for pivot guns, say 1,744 lbs. from the broadside. This is five times as much as it would receive from the battery, but, unless the land practice was very bad and the sea practice very good, even this ratio should not silence the battery as it stands.
42. Let us now, however, consider two points which will demonstrate weakness: (1) the addition to the squadron of two iron-clads, each carrying, say, five 9-inch muzzle-loading rifled guns on a broadside, making the squadron of the strength proposed at p. 243; and (2) that the weaker squadron would not take up a silencing position where it is exposed to the greatest amount of fire from the battery, but to the least.
43. The addition of these iron-clads means that 2,500 lb. more metal is discharged on the broad- side, giving a total of 4,241 lb., so that the ratio between the land and squadron fire is now increased from 1:5 to 1:12. Looking at it as a matter of guns, we have 32, weighing in all about 283 tons, opposed to 4, weighing about 20 tons, giving 8 times the number of guns and 14 times the amount of tonnage.
44. Again, the 7-inch guns of the battery cannot penetrate a 6-inch plate over 2,000 yards, at which range the calculated penetration is 5.9 inches. But while the formula for calculation has not been altered since it was evolved, armour plates have improved, so that we will not be far wrong if we omit the decimal and call the penetration at 2,000 yards to be 5 inches. Thus, at 2,000 yards and over, the iron-clads would shell the battery without receiving any corresponding injury, so that, con- sidering the inequality of the contest, we cannot expect the gunners in the battery to stand to their guns, and those guns not to be disabled.
45. If the battery cannot resist the attack of this squadron, when directed against the portion of the work delivering the greatest amount of fire, it will require a less powerful squadron to silence the Comparison of targets. fewer number of guns bearing on other selected positions. Two such positions can be taken up. The
* Not printed.
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