60 Variation of the Magnetic Needle. 



have had in view the benefit of those, who have but just en- 

 tered the thresliold of this important and extensive science. 

 Whether I have succeeded in the attempt, is submitted to 

 the decision of those, who are skilled in mathematical pursuits. 



Art. X. — Variation of the Magnetic Needle. 



We are happy to be able to lay before our readers the 

 following important papers, relating to the variation of the 

 needle. The first is from the " Transactions of the Albany 

 Institute," published in June, 1828. It contains a very in- 

 teresting document, exhibiting a series of observations on 

 the variation of the needle, made simultaneously at Boston, 

 Falmouth, and Penobscot, during a period of one hundred 

 and twenty eight years, namely, from 1G72 to 1800. It is 

 also accompanied by some important remarks, by the Hon. 

 Simeon De Witt; from which it appears that at Albany, and 

 at several other places in the state of New York, the needle 

 has, within a few years, ceased its declination towards the 

 north pole, and has begun to retrograde. 



The second paper, by Dr. Bowdilch, we borrow from the 

 "Memoirs of the American Acaden^y," for the year 1815. 

 It exhibits a series of observations made at Salem, Mass. 

 during the years 1805, 1808, 1810, and 1811, and contains, 

 interspersed, many valuable remarks, some of which relate 

 to the supposed change of declination in the needle from 

 east to west, as observed in the state of New York. 



In the third paper, we insert a few results obtained by our 

 lamented friend, Professor Fisher, from a series of observa- 

 tions instituted during the years 1819 and 1820. These, ta- 

 ken in connexion with those of Dr. Bowditch, indicate that 

 the retrograde movement of the needle, is not general, but 

 that, in this part of the country at least, the needle is still 

 approaching the pole of the earth.. 



I. Tahle of Variations of the Magnetic Needle^ copied from 

 one furnished by the late Gen. Schuyler to S. De Witt, 

 Surveyor General.— Presented 27th April, 1825. 



I now present to the Institute, for the purpose of having 

 it preserved, what I consider an interesting document. It is 



