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THURSDAY ISLAND.

The site suggested by the War Office for a battery on a hill at the west end of Thursday Island is Appendix No. 4. well adapted for concentrating the shore defences at one point. It is about 200 feet high, well placed so as to command all the anchorage in Ellis Channel, the middle of Normanby Sound, and a portion of Aplin Pass. It dominates the township and Government settlement to the south, as well as the ground to the north. Owing to the hill being very steep on three sides it could easily be rendered Site for battery inaccessible, and, although it is commanded by adjacent hills on Thursday, Hammond, and Prince of selected. Wales Islands, this is a danger which can best be guarded against when considering the details of the design for the battery. The hill has been cleared of trees, the ground is regular, stony, but free from boulders on the surface, and there is not much depth of soil. By lowering the general level about 15 feet sufficient space could be obtained for several guns.

As to the number and size of the guns, I do not think it is necessary or advisable to mount Number and size of five large and two medium guns, as proposed by the War Office. No doubt a numerous armament is guns and mode of

mounting. wanted, because the battery is exposed to the fire of light-draught vessels from three sides; but armoured ships could only attack from the Sound. This is a case where the expense of the shore defences must be cut down, as it is of equal importance to provide adequate means afloat to attack and follow up the enemy; consequently, I recommend the provision of two large armour-piercing and four medium guns, to be distributed as follows :—

1. Two medium guns to face south and command Ellis Channel, the anchorage and approaches thereto from west, east, and south.

2. Two large guns to face west and fire down Normanby Sound, their range of fire to include the western entrance to Aplin Pass and the anchorage in Ellis Channel.

3. Two medium guns to face north-west and fire down Normanby Sound and as far up Aplin Pass as the configuration of the ground will permit.

The two flank guns should be mounted so that they could fire inland, if required, to repel a land attack. The inner or south face of the work should be at a lower level on a shoulder of the hill, which is conveniently placed for the purpose. In this manner these guns would be protected from the reverse fire of vessels lying in Aplin Pass. The west and north-west faces could be defiladed by traverses from the surrounding hills, especially those on Thursday Island, which are situated at the rear of the proposed battery.

All the guns should be mounted en barbette in circular emplacements of the modern type, Description of protected by merlons and traverses. Cover should be provided where practicable to protect the battery. gunners from shell fire, to which the battery will necessarily be much exposed; but, as the guns will stand at a great height above the sea, the want of cover will be counterbalanced by this elevation. At the same time, cupolas could be added for the security of the large guns in the future, upon the plan which I understand is being worked out for large breech-loading ordnance mounted en barbette The usual magazines and stores should be provided. A permanent barrack for the garrison within the battery is unnecessary, as the work will be close to the Government settlement, where buildings could be appropriated or erected in time of war for its accommodation. As the rainfall is very heavy from January to March, no difficulty would be experienced in storing water in underground tanks.

It is worth considering whether the mounting of the four medium guns should not be deferred until war became imminent, spaces being left for them when designing the work. The guns could be stored in a shed; there would be less wear and tear of material, and a considerable reduction in first cost would be effected.

There should be at least three torpedo boats, of the improvised class-steam-launches which, in Torpedo-boats. time of peace, could be utilized for harbour service. I do not advise the provision of torpedo-boats of great speed. Boats of that class may be necessary for European warfare, but, in any opinion, they are not suited to the defence requirements of the Australian Colonies. Their great cost is not their only fault. They are not available for the rough and ready work required of steam-launches, which in peace time may be utilized for numerous harbour purposes. I prefer to make up by quantity for the inferiority in quality, so far as the power of offence is concerned. In fact, it is a question whether a number of steam-pinnaces, such as are supplied to ships of war, would not be well suited to the requirements of the defence at Thursday Island. However, before a decision can be come to on the point, the source from which the boats are to be supplied will have to be settled.

The gun-boat proposed might be of the "Staunch" class, of low speed and shallow draught, Gun-boat. armed with a breech-loading gun of the chambered pattern, capable of piercing such a thickness of armour as could be carried by ships likely to be sent to attack the Australian Colonies. It has been suggested that a gun-vessel with a higher speed and lighter armament would be preferable to the harbour defence gun-boat. The additional cost decides the point, as an increase in the speed necessi- tates a larger vessel and more powerful engines. No doubt, rapidity of manoeuvring power, where there are so many points to be guarded, would, in the event of attack by a large squadron, be of great advantage; but it would be safer, and in other respects more desirable, to have two low-speed gun- boats, or to lay out the money in the provision of additional torpedo-boats. Moreover, the armed vessel, which is necessary as a cruizer, would, under certain conditions, be a valuable auxiliary to the other floating defences.

The armed vessel should be a sea-going ship of the merchant class, possessing high speed, large Armed vessel. coal capacity, and sufficient strength to carry a light armament. Provided the requisite organization existed, a vessel of this class could be readily fitted out and commissioned on the outbreak of war, as the Australian mercantile marine is very numerous, and every day improving in quality, so far as speed is concerned. Speed, it is evident, is of the first importance for the naval defence requirements of Thursday Island. The organization necessary for insuring that, on the commencement of hostilities, the armed vessel should be forthcoming is not a subject, as I have before stated, which can be conveniently discussed in this Report.. It forms part of the general naval defence of Australia, a subject that I have thought it preferable to consider in a separate note, which will be found in the Appendix.

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