86 THE WANDERINGS OF THE NORTH POLE. 



the inoveiiieiits whicli tliis point imdergoes. Let me here endeavor to 

 describe the result at wliich he has arrived. 



In that paUieocrystic ocean which Arctic travellers have described, 

 where the masses of ice lie heaped together in the wildest confusion, 

 lies this point which is the object of so much speculation. Let us think 

 of this tract, or a portion of it, to be leveled to a plain, and at a par- 

 ticular center let a circle be drawn, the radius of which is about 30 feet; 

 it is in the circumference of this circle that the pole of the earth is con- 

 stantly to be found. In fact, if at different times, month after month 

 and year after year, the position of the pole was ascertained as the 

 extremity of that tube from which an eye placed at the center of the 

 earth would be able to see the pole of the heavens, and if the succes- 

 sive positions of this pole were marked by pegs driven into the ground, 

 then the several positions in which the pole would be found must nec- 

 essarily trace out the circumference of the circle that has been thus 

 described. The period in which each revolution of the pole around the 

 circle takes place is about four hundred and twenty-seven days; the 

 result therefore of these investigations shows, when the observations 

 are accurate, that the North Pole of the earth is not, as has been so 

 long supposed, a fixed point, but that it revolves around in the earth, 

 accomplishing each revolution in about two months more than the 

 period that the earth requires for the perfornmiice of each revolution 

 around the sun. 



The discovery of the movement of the pole which 1 have here 

 described must be regarded as a noteworthy achievement in astronomy, 

 nor is the result to which it leads solely of interest in consequence of 

 the lesson it teaches us with regard to the circumstances of the earth's 

 rotation. It has a higher utility, wliich the practical astronomer will 

 not be slow to appreciate, and of which he has, indeed, already experi- 

 enced the benefit. There are several astronomical investigations in 

 which the latitude of the observatory enters as a significant element. 

 Latitude is, in fact, at every moment employed as an important factor 

 in many astronomical determinations. To take one of the most simple 

 cases, suppose that we are finding the place of a planet in the observa- 

 tory. We deduceits position by measuring its zenith distance, and then 

 to obtain the declination the latitude of the observatory has, of coui-ser 

 to be considered. Now astronomers have hitherto been in the habit of 

 accepting the determination of their latitude which had been estab- 

 lished by a i^rotracted series of observations, and treating it as if it 

 were a constant. This method will be no longer admissible when astro- 

 nomical work of the highest class is demanded. No doubt, from the 

 sailor's point of view, an alteration in latitude which at most amounts 

 to a shift of 00 feet — not a quarter, perhaps, of the length of his vessel — 

 is immaterial. But in the more refined parts of astronomical work 

 these discoveries can no longer be overlooked ; indeed, Mr. Chandler 

 has shown that many discrepancies by which astronomers had been 



