14th. August 1872.
In accordance with the sanction given in Mr. Holland's letter of the 24th. June 1871, a copy of which is enclosed, and in pursuance of your interviews with my colleague. Mr. Vogel, I do myself the honour to open with you a correspondence on the subject there in mentioned.
I have, in the first place, to express to you my thanks for the able Memorandum which you forwarded last year on the Harbour Defences of New Zealand, and for the information contained in it, and in the other documents which you were so kind as to enclose.
I have now to request your further assistance on the same subject, which is one of so deep an interest to the Colony.
I must premise by informing you that, in the case of New Zealand, economy is to be most carefully considered by the Ministry, as the Country cannot afford to enter into an elaborate system of defence.
Not only is this economy to be observed in the material to be obtained, but the very choice of the system to be adopted must be subservient to this principle.
The forces upon which the Colony would have to depend, are - the Armed Constabulary, the Militia, and the Volunteers.
The first named are numerically weak and scattered about throughout the interior, in posts on the frontiers bordering on Native Territory. The Militia can barely be said to exist in the sea-port towns, and it is therefore, to Volunteers we should chiefly have to look for the defence of our harbours.
Of these, the Artillery is the branch which would most come into play; but its numbers are small, and the avocations of its members prevent such constant practice as would warrant thorough dependence being placed upon it, as our first and chief line of defence, were the scheme adopted of protecting the ports by land batteries.
It would thus be necessary to keep on pay a specially trained nucleus around which the Volunteers might muster, and this would involve an expenditure which is out of the question.
On the other hand, the numerous harbours of the Colony send forth a large number of sea-faring men,
well acquainted with every shoal and reef; and this matitime population would gladly give their services in a time of emergency.
A Commission which has lately sat to consider the subject of Defence has arrived at the conclusion that small plated gun-boats would profitably assist the scheme of Torpedo Defence;and that no difficulty would be found in manning such a class of vessels. The gunners required in this case would be fewer than for shore batteries, as it is proposed that these vessels would be of a size to carry only one gun.
I should feel obliged to you if you would favour me with the probable cost of such a kind of vessel, which is not intended to be a "Monitor", but only a craft of light draught, low in the water, sufficiently armoured to be able to resist the guns likely to be carried by the cruisers we would see on our coasts; possessing a fair rate of speed, and carrying a gun of such weight as to be able to inflict considerable injury.
I should also be glad to hear from you, some recommendations as to the nature of the torpedoes to be applied for; whether they should be electrical-self-acting, or only to be freed at will from shore, etc.
It would be of great assistance, if I could
be favoured with any instructions which may exist, concerning the details connected with the fixing, mooring, etc. of torpedoes; or with the manufacture of extempore appliances of the kind, for the use of whatever Corps whose duty it will be to attend to this important branch of defence.
As the progress of improvements in these submarine mines is very rapid, you will confer a favour by informing me occasionally of the latest inventions, as my object being to attain the best system in my power, it would be a source of great regret to me to find that I had incurred expenditure on means of defence which newer discoveries had rendered obsolete.