290 - Variation and Dip of the Magnetic Needle. 



Thus far, however, the reality of snch sounds, in any latitude, 

 is seriously questioned. The Aurora is a phenomenon well suited 

 to terrify the ignorant, and thus predispose them to connect with 

 it a thousand marvels, which have no existence : and it may even 

 so far excite the imaginations of the better informed, as to inca- 

 pacitate them fairly to judge of the fact ; since for the most part, 

 their impressions are previously formed. 



Tlie world is, after all, very much in the dark, in regard to all 

 that relates to this wonderful phenomenon. It is perhaps some- 

 what doubtful, whether, in our day, this darkness is to be enlight- 

 ened. We certainly live in a remarkable era, as it respects the 

 frequency and the splendor of auroral exhibitions ; and the phi- 

 losophers of the present time will grievously neglect their duty, 

 if they fail to take every possible advantage of the opportunities 

 of observation, which they are so happy as to enjoy. 



New Haven, Conn., Feb. 22,1838. 



Art. III. — On the Variation and Dip of the Magnetic Needle 

 in different parts of the United States; by Elias Loomis, Pro- 

 fessor of Mathematics and Natural Philosophy in Western Re- 

 serve College. 



About three years ago, T formed the design of collecting as far 

 as possible all the observations which had ever been made on the 

 variation of the magnetic needle within the limits of the United 

 States. I was of opinion that such a work would contribute 

 something to the cause of science, and might also be of practical 

 utility to public surveyors, who very generally in this country 

 make use of the magnetic needle in their surveys. The Connec- 

 ticut Academy of Arts and Sciences, gave me permission to write 

 in their name to gentlemen in different parts of the country re- 

 quesiing information on the subject. A great number of letters 

 were written, and to most of them, answers have been received. 

 The amount of information they embodied was not so great as 

 had been expected, I therefore hesitated about prosecuting my 

 original plan, and this, together with an absence of more than a 

 year from the country, is the reason that those observations have 

 not sooner been made pubhc. Although the article which is here 

 presented is very imperfect, being deficient in the number, and. 



