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Setting aside these views, I venture to think that the position marked A on the tracing* is the most suitable one in the harbour. There only is there deep water close alongside, and there only, so far as we could ascertain, was there sufficiently calm water at all seasons of the year to admit of a ship having her bottom cleaned and repairs effected. On the other hand, the best site for a coaling depôt (and in this opinion Captain Garforth entirely concurs with me) would be at the point marked B. The land there is widest, thus affording shelter from a sea-bombardment; it is close to the entrance; the water is calmer than any other part of the upper harbour, as the eastern branch of the island forms an efficient breakwater for the heavy seas that roll against it during the south-east trade; and when the north-west wind sets in, it leaves the water inside a line joining West Island and Point Marianne comparatively calm. There, too, there seemed to be facilities for constructing a pier for the conveyance of coal to the barges. The reef between high-water mark and 2-fathoms water at ebb tide is very flat and even. The pier would have to be about 150 yards long and 8 feet high at the head; it could be made of local timbers, and fixed to the reef.
The protection of these places may be effected either by forts and mines at the entrance or by local batteries. The perimeter of the island is about 33 miles, 30 of coast-line and 3 of entrance. The former need hardly be considered. It would be highly dangerous in ordinary weather to beach boats on the outside of the island, the surf running very high, and dashing with great force on the rugged coral in one continuous line of breakers from point to point. It is possible, however, in very calm weather, that boats' crews could be safely landed; and although it is unlikely that at enemy would chance on so favourable a time, still there remains the possibility of access to the island being had in this way, and precautions would be necessary to guard against it.
Now, with regard to the entrance, or distance between North-East and North-West Points, the revision of the soundings conducted under the orders of Captain Garforth, R.N., by Navigating Lieu- tenant J. Cuddy, R.N., during our recent stay, goes to show that in water from 5 to 7 fathoms deep near the entrance the coral has grown about 9 feet since 1837; that is to say, in many spots where the chart indicated say 6 fathoms, the depth is now only 44 fathoms, or thereabouts. This growth is not observable on coral near the surface. The 1 and 2-fathom patches on the chart seem to have altered but little, I am not aware of any new patches above water, and I understand there is a probability that some of the 1-fathom soundings indicated are not now to be found. This is not surprising, as many of the patches are very small, and could easily be washed away as soon as they grew high enough to be affected by the heavy seas that roll in.
The passages between Middle and East Islands and the latter island and North-East Point have thus become considerably more dangerous than they were when last surveyed, and this may account for the loss of the "Hampshire" in attempting to pass out of the harbour in 1869.
The subject of these soundings is fully dealt with by Captain Garforth, R.N., in his Report, and I only allude to it in general terms as connected with the defensibility of the entrance.
There is no passage between North-West Point and West Island. The reef between is either bare or nearly so at low water, and is very uneven. The passage between West and Middle Islands is deep and safe. is 2,000 yards wide at its narrowest part, following the 5-fathom line.
It
There are three islands and two headlands to be considered as sites for batteries. Of these, North-West Point may be at once put aside, as it is too distant from any passage; and for the same reason Middle Island may be thrown out of account, the reef stretching out so far to the westward as to cause a loss of the best ranges of any guns placed there.
East Island, which is the only one having any substance on which I would like to erect any heavy work, is also useless, because boats or light craft entering either of the two eastern passages must, on account of the numerous patches in front, come within range of guns on North-East Point, which would therefore be a better site for a battery.
In the War Office Memorandumt two projects for entrance defence are alluded to: first, "a turret on one of the rocky patches near the centre of the four entrances; and the other, the occupation of West Island."
The former I venture to think quite impossible; the young coral is soft, and it would require a wholly different survey than is ever attempted for navigation purposes to give any idea of the actual fluctuations of the surface of coral patches. It is no uncommon thing to sound 7 fathoms alongside a rock nearly awash; and unless soundings were taken all over the surface, no correct sections through these patches could be made. No idea can be formed of the actual shape of any of these patches from the dotted spots on the chart.
It is more than likely that in the middle of many of them 8 and 10 fathoms might be sounded. At any rate, there is no patch near enough to the surface or large enough to form the base of a turret. But more dependence seems to have been placed on West Island, and certainly, so far as appearance goes, its situation seems to deserve attention. However, I must wholly dissent from any project to put a heavy battery on that island. It is a wretched little place, not more than 4 or 5 feet high in the middle; the whole substance is rocky, loose-looking coral. I doubt very much if any solid foundation could be found. Then it is exposed to 180° of attack from without, and all the water in range within the harbour, the portion defiladed by the land only occupying some 45° of the whole circle. To protect such a zone would require more space than is available. The chart shows its size at low water. I went to it, but could not land, on account of the difficulty of getting a boat near enough. I was, however, fully satisfied that it was quite too small to place a heavy battery on it, and it was with that particular object in view that I went there, in company with Captain Garforth.
Such an island of solid rock would no doubt give space enough. The batteries and protective works could stand right out to low water, at any rate; but on such coral it would be most dangerous to try such experiments. I know the coral close to the island, on the reef between it and North-West Point, is not much heavier than pumice-stone, and crumbles very easily. There are veins of very hard coral here and there, but for the most part it is quite soft. I would be afraid that, however
[1103]
* Plan not printed.
+ No. 64.
3 C
Appendix No. 4.
DIEGO GARCIA,
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