166 Transactions.— Miscellaneous. 
serious consideration to guard each place, as beyond the ordinary route 
through the Rangitoto channel we have the eastern passage on both sides of 
Moto Ihi, the Waiheke Channel and the sand-spit, but the whole of these 
converge to a point between Brown Island and Rangitoto, thus practically 
reducing the points to be guarded to two, and these I will deal with 
separately. Outside of a line drawn from the reef to the mainland no point 
can be obtained by which the elevation of a gun couldaccurately be brought 
to bear upon Auckland, but inside that line several points come in to view 
which would prove of value for that purpose, though distant from the city, 
notably the new hospital, All Saints Church, and Parnell, therefore our first 
defence must be outside this line, and that will commence from the reef. 
Here the safe working channel does not exceed three-quarters of a mile, and 
at this place I would place the first line of torpedoes, inside of which I 
would have a second, third, and fourth line decreasing in number and 
coming to an apex, all being connected with the station by insulated 
wire in the way I will now describe. The safe working channel 
being about 1,500 yards wide, I would place say 14 torpedoes in the 
first line, 12 in the second, 8 in the third, and 5 in the fourth, the electric 
connections being carried to a high station, for instance, the North Head, 
which is admirably suited for the purpose. If this station was decided 
upon it would be the only one required for the defence of both entrances, as 
I will show presently. 
On the high cliffs approaching the lake, which reach an elevation 
of sixty or seventy feet, will be required an observing station with one 
operator to give the signal to the main station at the North Head, by 
electric alarum, as to the enemy’s approaching the first line of defence, and 
the same. with respect to the second and third. From the main station it 
would be seen by the use of a theodolite or eross-wired telescope (the 
position of the torpedoes being accurately known) whether the enemy was 
sufficiently in position for the firing of the nearest torpedo, if not she would 
be permitted to come towards the second line, and presuming she had gone 
midway between the intervals in the first line she would now be approaching 
exactly to one in the second line, and on the signal being given from the 
observing station that she was already on that line, and its being seen from 
the main station that she was over or close to the position of the torpedo, 
it would simply require the depressing of the electric key to insure the 
diseharge of the torpedo and probable ruin of the vessel. 
With respect to the defence of the Eastern passage, I wish to draw 
attention to the narrowing of the Koreho Channel about 1j miles N.E. of 
the Bean Rocks, or nearly midway between that spot and Brown Island, 
and also that in the centre of this channel is a very shallow bank of only 
