NATURAL PHILOSOPHY. 147 



the outlay. And what, I may be asked, is the general conclusion to be drawn 

 as the result of this investigation of the law of the squares applied to sub- 

 marine circuits ? In all honesty, I am bound to answer, that I believe nature 

 knows no such application of that law ; and I can only regard it as a fiction 

 of the schools, a forced and violent adaptation of a principle in physics, good 

 and true under other circumstances, but misapplied here." 



DE. SCOEESBY'S OBSEEYATIONS ON THE YAEIATION OF THE 



COilPASS. 



Dr. Scoresby, of England, has, it is well known, devoted much time and 

 attention during the last few years to an examination of the phenomena of 

 magnetism in relation to the compass, and published several able communi- 

 cations on the same subject. During the latter part of the year 1855, with a 

 view of aiding research, the British and Australian Steam Company tendered 

 to Dr. S. a free passage in an iron steamer, the Eoyal Charter, to Australia, 

 and extraordinary facilities for conducting experimentation and research. 

 The proposition so made was accepted, and the voyage having been success- 

 fully completed, Dr. Scoresby has recently published a report of the results, of 

 his magnetical researches during the voyage of the Royal Charter to Australia 

 and round the world. The Eoyal Charter, it should be noted, is an iron ship, 

 of the clipper class, with auxiliary steam power, belonging to the Liverpool 

 and Australian Navigation Company. She is 334 feet hi length on deck, and 

 42 hi breadth, and 2,787 tons measurement. The compasses of the Royal 

 Charter, observations on which were an important object of Dr. Scoresby's 

 inquiries, were four in number ; the steering compass, adjusted by magnets on 

 Mr. Airy's principles, 68 feet from the stern ; another adjusted compass (called 

 the " companion compass") 89 feet ; a standard compass on the deck house, 

 unadjusted, 181 feet from the stern ; and a compass aloft, 42 feet above the 

 poop deck. 



The leading objects contemplated by Dr. Scoresby in his recent undertaking 

 were, to verify or test his theoretic views and results of inductive researches 

 on the phenomena of magnetism with relation to the compass, especially as to 

 the ' retentive quality" so highly developed in iron ships in the process of con- 

 struction, with the changes in such magnetism views which he had first 

 placed before the public at the meeting of the British Association at Oxford in 

 1847, and since then in his "Magnetical Investigations" published in 1852, 

 and in various other forms ; and to test also his plan of a compass aloft, first 

 proposed in his account of discoveries on the eastern coast of Greenland hi 

 1822, for the avoidance of the ship's attraction, and for obtaining correct com- 

 pass guidance, so essential to safety in navigation. Four plans or processes 

 were adopted by Dr. Scoresby for the determination of the facts, as to the 

 nature and changes of the ship's magnetic condition, viz. comparisons, almost 

 daily, of the four compasses described; experiments on the ship's external 

 magnetism, as indicated by her deviating action on a compass placed first near 

 the upper edge of the top plating, and then gradually let down towards the 

 water's edge, such experiments being made in different parts of the ship's 



