166 Transactions. — Miscellaneous. 



serious consideration to guard each place, as beyond the ordinary ronte 

 through the Eangitoto channel we have the eastern passage on both sides of 

 Moto Ihi, the Waiheke Channel and the sand-spit, but the Vv^hole of these 

 converge to a point between Brown Island and Eangitoto, 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 could accurately be brought 

 to bear ujpon 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 h'om 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 

 comuig 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 admhably 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 cross-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 a]pproaching 

 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 

 discharge 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 1^ miles N.E. of 

 the Bean Eocks, or nearly midway between that sj^ot and Brown Island, 

 and also that in the centre of this channel is a very shallow bank of only 



