98 Notice of the late Aurora Borealis. 



time, move through a space equal to its distance from the surface 

 which reflects it: this distance maybe several thousands of miles." 



Upon this supposition with regard to the aurora generally, 

 the luminous arches are accounted for as follows. 



"Their form, position, motion, and time of appearing, all con- 

 cur in pointing it out to be the light of the sun reflected by the 

 spherical surface of the earth, and again reflected back on a dif- 

 ferent part of it by the atmosphere. From the regular form of 

 the arches, it is probable that the surface from which they were 

 reflected was that of the ocean, which stretches in the direction 

 in which the sun was during their appearance. But later in the 

 evening, when that uniform surface had passed out of the line of 

 direction by the rotation of the earth, and the icy regions of the 

 north pole had intervened, the sun being reflected from a bro- 

 ken unequal surface, the arch was also broken into streamers of 

 the usual appearance. It will be obvious, that without the refrac- 

 tive power of the atmosphere those phenomena could have no 

 existence, because in that case the reflected rays of the sun could 

 fall no where except in that space enlightened by his direct rays; 

 but by refraction those rays falling upon the verge of the enlight- 

 ened hemisphere, must, when reflected, be bent into the dark 

 hemisphere." 



Whether this reasoning be correct or otherwise, is left for 

 others to decide. The following extracts of letters on the 

 subject, with which I have been favored, by the venerable 

 E. A. Holyoke, M. D. LL. D. of Salem, Mass. whose years 

 now number more than a century,* furnish interesting descrip- 

 tions of these phenomena which occurred in old times, and 

 mention facts which would rather favor the theory that they 

 are attributable to electricity. 



Extract of a letter from Dr. Holyoke, dated Salem, Sept, 



19, 1827. 

 ********** 



About fifty or sixty years ago, I observed early in the evening, 

 an unusual and remarkable luminous band, or stripe in the 

 firmament, extending from about the N. N.W. point of the 

 horizon, through the zenith, to the opposite E. S.E. point. 

 The color was that of a white cloud. It continued station- 



* It is scarcely necessary to remark, except possibly to some of our readers in 

 Europe, that Dr. Holyoke has been during a large part of his centurial term, 

 distinguished as an eminent physician and friend of useful knowledge. — Ed. 



