AURORA BOREALIS. 335 



current was fit times so strong that it was necessary to connect the lines with 

 the caith in order to save the apparatus from destruction* 



C. Whi'U passed througli the animal system, electricity communicates a 

 shock which is quite peculiar and characteristic. During the auroras of August 

 28 and Septemher 2, some of the telegraph operators received severe shocks 

 when they touched the telegraph wire^. At Philadelphia the current gave a 

 severe shock. At "Washington, D. C, the telegraph operator received a severe 

 shock, which stimned hira for an instant.t 



D. A current of electricity develops magnetism in ferruginous bodies. The 

 aurora of September 2 developed magnetism so abundantly and so steadily that, 

 on several lines, it was used as a substitute fur a voltaic battery in the ordinary 

 business of telegraphing. The intensity of this effect was estimated to have 

 been at times equal to that of 200 cups of Grove's battery upon a line 230 miles 

 in length. In Switzerland the currents were at least three-fold the ordinary 

 current employed in telegrapliing| 



E. A current of electricity detiects a magnetic needle from its normal position. 

 In England the usual telegraph signal is made by a magnetic needle surrounded 

 by a coil of copper wire, so that the needle is deflected by an electric current 

 flowing through the wire. Similar deflections were caused by the auroras of 

 August 29 and September 2, and these deflections were frequently greater than 

 those produced by the telegraph batteries. § 



F. A current of electricity produces chemical decompositions. During the 

 display of September 2 the auroral influence produced the same marks upon 

 chemical paper as are' produced by an ordinary voltaic battery ; that is, the 

 auroral influence decomposed a chemical compound, the cyanide of potassium. 

 The same effect was produced by the aurora of February 19, 1852. |( 



G. Certain bodies, such as fluor spar, the solution of sulphate of quinine, and 

 several vegetable infusions possess the remarkable property of so dispersing 

 some part of the light passing through them that the course of the luminous 

 rays become visible, as though the body were self-luminous. This phenomenon 

 has been icxvacA Jluorcsccnr.e. This fluorescence is produced in a very remarka- 

 ble degree by the light of an electric discharge, and the saiue effect is found to 

 be produced by the light of the aurora. On the 14th of March, 1S5S, during 

 the exhibition of a brilliant aurora. Professor Robinson, of Armagh observatory, 

 found that a drop of disulphate of quinine on a porcelain tablet seemed like a 

 luminous patch on a faint ground ; and crystals of platino-cyanide of potassium 

 Avere so bright that the label on the tube which contained them (and which by 

 lamplight could not be distinguished from the salt at a little distance) seemed 

 almost black by contrast. These effects were so strong in relation to the actual 

 intensity of the light that they appeared to afford additional evidence of the 

 electric character of the aurora.^ 



The preceding facts are regarded as proving, conclusively, that the fluid de- 

 veloped by the aurora on the telegraph wires is indeed electricity. This elec- 

 tricity may be supposed to be derived from the aurora either by transfer or by 

 induction. If we adopt the former supposition, then the auroral light is cer- 

 tainly electric light. If we adopt the latter supposition, then we must inquire 

 what known agent is capable of inducing electricity in a distant conductor. 

 We know of but two such agents — magnetism and electricity. But the auroral 

 fluid is luminous, while magnetism is not luminous. We seem, then, compelled 

 to admit that the auroral light is electric light. 



* American Journal of Science, n. s., v. 32, p. 32.3. 

 t American Journal of Science, n. s., v. 32, p. 323. 

 + American Jonrual of Science, n. s., v. 32, p. 324. 

 ^ American Journal of Science, n. s., v. 32, p. 324. 

 II American Journal of Science, n. s., v. 32, p. 324. 

 liLond. Ed. and Dub. Pliil. Mag., v. 15, 4tJi ser., p. 326. 



