Facts from the Arcana of 'Nature. 91 



have heretofore over-estimated this element of dubiety by 

 about sixteen seconds. 



It is stated, that "In middle latitudes of the northern 

 hemisphere, when the sun is eastward of the meridian dur- 

 ing the forenoon, the needle points more eastward than on 

 the average of the twenty-four hours ; also, when west, 

 during the afternoon, it points more to the westward." 

 " The angle of the dip, like that of the variation, changes its 

 value even at the same place, following of course the motion 

 of the magnetic poles, which from observations made by 

 Scoresby, Parry, Ross, and others in high latitudes, appear 

 to have a motion westwards, the annual amount of which is 

 11' 4'V It has, however, been conjectured that there are two 

 distinct poles of magnetic attraction in arctic regions, one 

 defined as the American, the other the Asiatic, presently 

 many hundred miles apart, but apparently approximating 

 towards perhaps ultimate coincidence. " The diminution 

 of the magnetic dip noted in London for the last half century, 

 is progressing with great regularity at a definite small annual 

 rate." All such phenomena indicate the ceaseless operation 

 of natural laws as yet unrecognised or imperfectly under- 

 stood by science, but which may mark physical changes of 

 vast and startling import to mankind. 



Mr. Airy, the Astronomer-Royal, in his Report to the Board 

 of Visitors for 1861, observes, " The Transit Circle and Colli- 

 mators still present those appearances of agreement between 

 themselves, and of change with respect to the stars, which 

 seem explicable only on one of two suppositions, that the 

 ground itself shifts with respect to the general Earth, or 

 that the axis of rotation changes its position" Again, in 

 1863, he remarks, that " Some great cosmical change seems 

 to have come upon the Earth, particularly affecting terres- 

 trial magnetism." 



The greatest vertical depth to which experiment by boring 

 has tested internal heat is as yet stated to be but 2,100 feet, 

 or about one ten thousandth part of the earth's radius, a limit 

 far too fractional to admit of positive conclusions being 

 formed thereon, as to the increasing internal heat of our globe 

 towards its centre. Admitting, however, that progressive 

 elevation of temperature is detected in certain localities, to that 

 depth, the results of numerous experiments, undertaken to 

 test the temperature of the ocean in various parts of the 

 world, at vastly greater depths, are conclusively adverse to the 

 doctrine of the internal heat increasing in proportion to 



