INAUGUBAL ADDRESS. 11 



of a great submarine plateau ; but liow far that plateau 

 extends connecting the southern islands towards the great 

 Antarctic land^ and how far to the eastward, is still an 

 unsolved question. Then, again, the direction and in- 

 tensity of the magnetic currents in and around New Zea- 

 land requires further close investigation, which can only be 

 controlled from an observatory. Even iu the matter of 

 secular changes in the variation of the compass, we find that 

 the marine charts instruct that an allowance of increased 

 easterly variation of 2' per annum must be made, and, 

 as this has now accumulated since 1850, it involves a very 

 sensible correction to be adopted by a shipmaster in making 

 the land or cruising along the coast ; but we find from the 

 recently-published work of the '^ Challenger ^' that this 

 tendency to change has for some time back ceased to affect 

 the New Zealand area, and, as the deduction appears only 

 to have been founded on a single triplet observation of the 

 dip taken at Wellington and one azimuth observation taken 

 oft' Cape Palliser, it would be Avell to have this fact verified. 

 With regard to the local variation in the magnetic cur- 

 rents on land and close in-shore, the necessity for exact 

 survey is even more imperative. Captain Creak, in his 

 splendid essay on the magnetic observations of the " Chal- 

 lenger '^ Expedition, quotes the observations made by the 

 late Surveyor-General, Mr. J. T. Thomson, at the Bluff 

 Hill, which indicate that a compass on the north side was 

 deflected more than 9° to the west, while on the east side 

 of the hill the deflection is 46° to the east of the average 

 deviation in Eoveaux Strait. He remarks that if a similar 

 island-like hill happened to occur on the coast, but sub- 

 merged beneath the sea to a sufficient depth for navigation, 

 serious accidents might take place ; and he instances a case 

 near Cossack, on the north coast of Australia, where H.M.S. 

 '^ Medea," sailing on a straight course in eight fathoms of 

 water, experienced a compass deflection of 30° for the dis- 

 tance of a mile. A glance at the variation entered on the 

 meridian-circuit maps of New Zealand shows that on land 

 we have extraordinary differences between different trig, 

 stations at short distances apart. In close vicinity to 



