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Appendix No. 4.
ASCENSION.
Inclosure in No. 11.
Report on the Defences of the Island of Ascension, visited in conjunction with Captain A. J. Kennedy, R.N.
THE Confidential Memorandum on the Island of Ascension, by Colonel J. H. Smith, R.E., dated War Office, 9th April, 1881,* and issued by the Inspector-General of Fortifications, is taken as the basis of this Report.
2. The existing defences of Ascension differ from, and are in excess of, those referred to in the War Office Memorandum, as follows:-
3. Hay's Fort.-This is a battery originally for three 68-pounder smooth-bore guns on garrison carriages, firing en barbette from ground platforms. It is now occupied by one 64-pounder muzzle- loading gun on naval slide carriage (front pivot); the parapet is straight to enable the gun to work in a semi-circle, and three weak embrasures have been added (revetted with casks), directed on (a) to the jetty-head, (b) seawards, and (c) to Catherine Point.f
4. The site of the battery is the top of a small semicircular crater, having a diameter of about 40 yards, open to the land side, the height above sea-level being about 110 feet. It is 400 yards west of the jetty. The interior of the crater would afford satisfactory cover for a store magazine, referred to hereafter.
5. This position is good for two heavy rifled guns en barbette, each with about 120° range, as it can see over Fort Thornton and the naval stores to the anchorage and Clarence Bay, Comfortless Cove, &c. ; and guns mounted here could bear on a vessel in every position she could take up for the purpose of firing on the naval establishment, the buildings of which are near the beach, and fully exposed to view from the sea.
6. Fort Thornton is a masonry battery for seven smooth-bore guns on high traversing platforms, composed of two parallel parapets (facing outwards), each prepared for three guns to flank the coast; these parapets are 20 yards apart (crest to crest), and are joined into a salient in which to mount the seventh gun.
7. The work is well built, and forms an illustration of what was a type of construction forty years ago. It is not traversed, but the two rearmost guns on each face are 3 feet lower than the others, presumably for purposes of defilade.
The guns (smooth-bore) have been withdrawn and sent to England some years back, and the battery is dismantled.
8. A square masonry block-house (36 feet side) is situated 20 yards behind the battery. This is a most prominent feature in the landscape; it is used as the principal magazine of the settlement, and now contains 25,000 lbs. of powder. The walls being only 4 feet thick, and exposed to view from all directions, would render imperative the emptying of this magazine whenever hostilities are imminent.
9. The site of the battery and block-house is the top of an isolated and salient rocky bluff, which is practically level, and about 70 feet above the sea. Its length, which is perpendicular to the coast- line, is about 100 yards, while its breadth (available for building) is only about 40 yards.
10. The position is good, as it is salient, and commands an unobstructed view of the sea to the coast each way.
Its drawbacks are (1) its narrow front of only 40 yards, and (2) that any fire directed on it from the sea would search out the most important buildings, viz., the naval store, the victualling yard, factory, condensers, &c., which are grouped together in rear.
11. Fort Warren is a battery, 25 feet above the sea, mounting two 64-pounders on wood truck carriages, firing en barbette; the object is to flank Clarence Bay and beach. The terreplein of the guns is 6 feet above the ground, communication being by masonry steps. This battery is on the right rear of Fort Thornton, the hill site of which well screens the battery from any fire directed on to Fort Thornton.
The left gun fires seawards as well as flanks the beach; this arrangement renders both guns liable to enfilade from the sea.
12. The battery is well placed and is efficient, but should be used only for flanking purposes; this could be done by a bonnette on the seaward parapet of the left gun, which would then form an efficient epaulment to screen the guns both from view and from fire from the sea.
13. Fort Murdoch is a well-placed two-gun battery, situated on a spur of Cross Hill about 280 feet above the sea. It is about 700 yards in rear of Fort Thornton, and has an unobstructed view of the whole settlement and of the coast-line from Comfortless Cove on the right to Catherine Point on the left.
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Two 64-pounder muzzle-loading guns are here mounted on wood carriages, working on wood ground platforms; they fire en barbette.
14. In combination with Warren Battery, this work forms a satisfactory protection from an attempt to destroy the stores, &c., of Georgetown by a party which may have effected a landing.
15. The parapet of Fort Murdoch is weak, being only 8 feet thick, but considering the retired nature of the site, as regards hostile fire from shipping, it does not seem necessary to strengthen it. This, however, could be done with facility merely by retiring the low masonry interior slope, and shifting the platforms, there being sufficient level space in rear for so doing; the parapet cannot be strengthened to the front on account of the slope of the hill there.
16. Cross Hill is an isolated conical hill, 870 feet high, formed entirely by the scoria, &c., thrown from an extinct volcano, the crater of which is situated on its rear (or landward) side. Being subject to the constant influence of the trade wind, the ejected matter drifted towards the north-west or sea side, and the windward or land side of the crater has disappeared, the lee side thereof now forming the landward side of the hill, and is too steep and rugged to be assailable. The other slopes of the hill vary from 25° to 35°.
* No. 12.
† Plan not printed.
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