<)6 Proceeding i!< of the Royal Society of Victoria. 



Australia and Bezout Island, and Captain Moore has made a 

 tborougli magnetic survey of the locality, and in a letter 

 dated 22nd June this year, has sent me a copy of the official 

 account of his work. As tins subject will be interesting to 

 the Society, and of importance to our nautical men going 

 west about to Northern Australia, or the Straits, I now give 

 (^)ptain Moore's account verbatim : — 



Magnetic Shoal near Cossack, W.A. 



The area of magjietic disturbance near Cossack, exhibits 

 the characteristics of red magnetism, as if there was a con- 

 gestion or concentration of the magnetic elements, due to 

 the Southern Hemisphere. It seems appropriate, therefore, 

 to call it a "Magnetic Shoal"; and to treat it gi-aphically, 

 as if it was an elevation of the bottom of the sea or area of 

 "shoal" water, the soundings being the "deflections" of the 

 compass needle. 



Woi'ked out thus, it was found that the magnetic shoal 

 developed the following features: — (1) An area 4 miles long- 

 north-east, and south-west by 2 miles broad ; witli a depth 

 of 8 to 9 fathoms at low water springtide ; bottom, quartz 

 sand, over which the compasses are deflected one degree or 

 more. 



Within the above, an area 3 miles long north-east and ' 

 south-west, by half a mile to 1| miles broad, over which 

 compasses are disturbed half a point or more. 



Within the above: — (1) A line of maximum easterly 

 repulsion, about 2^ miles long, over which the north-seeking 

 end of the needle is violently repelled to the east, in several 

 ])laces over 40°, and in one place 56°. (2) A line of 

 maximum westerly repulsion, about 2^- miles long, over 

 which the north-seeking end of the needle is repelled to the 

 west, to the extent of about one-half the easterly repulsion. 

 (.3) Between these two lines, which are from 200 yards to 

 GOO yards apart, a line of no repulsion '1\ miles long, over 

 which the needle points to the true north, and the direction 

 force is very small. This is called the "axis," or "line of 

 vanished repulsion." (4) A point on this line, about one 

 mile from the south-west end of the magnetic shoal, where 

 tiie intensity is greatest, which is called the " focus." The 

 axis, or line of vanished repulsion, is inclined to the true 



