NATURAL SCIENCES OF PHILADELPHIA. 175 



conviction that T actually saw electricity, whatever that may be, transferred 

 bodily from north to south. But did these mild but swift electric clouds 

 take the path along the top of the atmosphere, or along the magnetic curves ? 

 They were certainly quite distinct from the tall continuous streamers. I in- 

 cline to believe that they ran along the top of the atmosphere, and that they 

 were nearer than the streamers. But by mere vision the relative nearness of 

 such objects cannot well be distinguished; we cannot tell the relative near- 

 ness of a planet and a fixed star by simple inspection, although the one may 

 be several hundred thousand times farther otf than the other. 



In Prof. Loomis's description of the great auroral display of Aug. 28, 1859, 

 he records some very remarkable observations, and reproduces the diagrams 

 fihosving the deflected course {lursued by some streams and flashes of electric- 

 ity.* Such tortuous streams would be impossible in the magnenc curves. But 

 they are what should be occasionally looked for when the electric fluid passes 

 through and over the upper regions of the atmosphere. That atmosphf^re we 

 know is composed of various strata and various currents, some dry and some 

 moist, some moving one way and some another, and some charged with 

 electricity more than others. Therefore a stream of electricity floating 

 through or over the rare upper regions of the atmosphere, and meeting these 

 various strata and currents, must be affected differently, and sometimes made 

 to produce just such curved phenomena as are presented in those descriptions. 



Lightning down the side of a tree takes a tortuous path from the grain of 

 the wood, or even of the bark. 



The upper path, the magnetic curves far away above the atmosphere, pur- 

 sued by the electric fluid in passing from the north to the south, I do not now 

 discuss. Like many other kindred auroral topics, it is not within the scope 

 of this short paper. That path has been ably treated by B. V. Mersh, Esq., of 

 this city, and by Prof. Loomis of Yale College, when describing the great 

 auroral display of 1859 in the American Journal of Science and Arts, where 

 both those gentlemen have given references to other authors. 



The CONSTANT passage of the electric fluid from north to south is indicated 

 by the frequent irregular deflections of the magnetic needle, and by the fre- 

 quent auroral displays in high northern latitudes. Prof. Loomis portrays a 

 zone around the northern region of the globe, where the aurora is seen eighty 

 times in a year, as the highest maximum average. But this number seems to 

 me to be too small. Many observers speak of their appearance almost nightlv. 

 In latitude 70° X., at Bossekop, in Alten Bay, on the coast of West Finmark, 

 M. Lottin observed one hundred and forty-three auroras during an interval of 

 two hundred and six days, between September, 1838, and April, 1839. During 

 the long niglit of seventy times twenty-four hours, from Nov. 17 to Jan. 25, 

 the aurora was visible sixty-four times. On other occasions within that same 

 period, when the sight of the aurora was impossible on account of thick 

 clouds, it was proved to exist by disturbances of the magnetic needle. At 

 Fort York, in 1780, Umfreville says " there were very few nights without an 

 aurora." Chapell in 1814, when giving his experience, says "the nights were 

 constan'ly illumined by the aurora." Henderson says he saw the auroras in 

 Iceland in 1814-15 almost every clear night. Such is the testimony of others, 

 but in this short paper 1 cannot quote. In Prof. Loomis's collections about 

 the great display in 1859, several similar expressions may be found, and also 

 in the collection of Mr. Peter Force in the 8th volume of the Smithsonian 

 Contributions. During the summer of 1868 I spent six weeks on the Sague- 

 nay river or its near vicinity in Cannda. being part of the time at Grand Bay 

 and Chicoutimi, more than a hundred miles due north of Quebec. There the 

 aurora appeared almost every evening ; indeed, its appearance was the rule 

 and its absence the exception. But the displays were not strikingly grand. 

 I remarked that on the Saguenay they were much more frequent than when I 



* Am. Journal of Science and Arts, vol. 31, pp. 84, 85. 



1869.] 



