AUSTRALASIAN ASSOCIATION. 87 



accumulated since 1850 it involves a very sensible correction to be 

 adopted by a shipmaster in making the land or standing 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 at Cape Palliser, it would be well 

 to have this fact verified. With regard to the local variation in the 

 magnetic currents on land and close in shore, the requirement for 

 exact survey is even more imperative. Captain Creak, in his splendid 

 essay, 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 deg. to the west, while on the east 

 side of the hill the deflection is 46 deg. to the east of the average 

 deviation in Foveaux Strait. He adds that if a similar island-like hill 

 happened to occur on the coast, but submerged 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, when 

 H.M " Medea," sailing on a straight course in eight fathoms of water, 

 experienced a compass deflection of 30 deg. for the distance 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. For instance, in our 

 close vicinity, at Mount Pleasant, behind Godley Head lighthouse, at 

 the entrance to Lyttelton harbour, the variation is only 9 deg. 3 min. 

 east, or 6 deg. less than the normal ; while at Rolleston it is 15 deg. 

 33 min., and at Lake Coleridge 14 deg. 2 min. In Otago we have still 

 greater differences recorded, for we find on Flagstaff Hill, which is an 

 igneous formation, 14 deg. 34 min., while at Nenthom, thirty miles to 

 the North, in a schist formation, we find an entry of 35 deg 41 min. 

 In view of the fact that attention has been recently directed to the 

 marked effects on the direction and intensity of the terrestrial magnetic 

 currents of great lines of fault along which movements have taken 

 place, such as those which bring widelv different geological formations 

 into discordant contact, with the probable production of mineral veins, 

 this subject of special magnetic surveys is deserving of being under- 

 taken in New Zealand. In Japan and in the United States of 

 America the results have already proved highly suggestive. A 

 comparison between this country and Japan by such observations, 

 especially if combined with systematic and synchronous records by 

 modern seismographic instruments would be of gre.it service to the 

 physical geologist. There are many features in common, and many 

 quite reversed in the orographic and other physical features of these 

 two countries. Both are formed by the crests of great earth waves 

 lying north-east and south-west, and parallel to, but distant from 

 continental areas, and both are traversed by great longitudinal faults 

 and fissures, and each by one great transverse fault. Dr. Nauman, in 

 a recent paper, alludes to this in Japan as the Fossa Magna, and it 

 corresponds in position in relation to Japan with Cook Strait in relation 

 to New Zealand. But the Fossa Magna of Japan has been filled up 

 with volcanic products, and is the seat of the loftiest active volcano in 

 Japan. In Cook Strait and its vicinity, as you are aware, there are 

 no volcanic rocks, but there and southward, through the Kaikouras, 



