1882.] 289 [Lewis. 



The influence of an aurora upon the telegraph wix-es is very different 

 from tlie local and transitory effects of a thunderstorm, and can always be 

 recognized. The electrical disturbances at Philadelphia continued from 

 midnight until eleven o'clock on Monday morning. At the office of the 

 Western Union Telegraph Company in New York it is reported that the 

 ■wires began to be affected soon after ten o'clock and that before eleven 

 the wires in every direction were frequently interrupted. It is said that 

 whenever an auroral current of like polarity with the battery reached the 

 wires it neutralized the current completely and broke the circuit. In like 

 manner auroral currents of opposite polarity, which were both powerful 

 and frequent, would intensify the current to such a degree as to make it 

 unsafe to use the wires. At such times brilliant sparks appeared at the 

 ends of the keys and repeaters, which would soon burn the instruments if 

 not disconnected. The change of polarity in the auroral current was very 

 intermittent. Sometimes it occurred very rapidly, and at other times ten 

 or fifteen minutes would intervene without change of current. Similar 

 electrical phenomena are reported from many parts of the country, indi- 

 cating an electrical storm of great extent. 



There was no wind at Philadelphia during the aurora, and the mild 

 spring-like weather before and during the few days since has undergone 

 no change of consequence. Observations of this nature upon a number 

 of auroras have led the writer to think that the popular idea that the 

 aurora is either the cause or the result of change of weather is a flillacy. 

 Local thunderstorms and several severe tornadoes have however occurred 

 since the aurora in several parts of the country. 



On the night of April 19-20 a second aurora appeared. There had been 

 a severe thunderstorm early in the evening — the occasion of loss of life 

 and property in different portions of the State — and some time after the 

 sky had cleared, at about 1.30 A. M., there appeared a fine aurora, with 

 high and bright streamers. As before, the telegraph wires were affected, 

 the disturbance at Philadelphia continuing from 1 A. M. to 11.30 A. M.* 



The occurrence of remarkable auroral displays at this time is a striking 

 confirmation of the periodicity of those phenomena. It is just ten years 

 since the last auroras of importance occurred, and the period of 10 to 12 

 years between maximum auroral displays may be regarded as firmly es- 

 tablished. The coincidence of this period with that of most numerous 

 sunspots shows a direct connection between the electrical condition of the 

 earth and the sun. At the present time the sun is exhibiting remarkable 

 disturbances. Upon the sun's disc are numerous and large spots which 

 are continually changing in shape, and are traversed by solar cyclones of 

 unusual energy. Large groups of sunspots are now visible to the naked 



* The writer is indebted to the offlcers of the Western Union Telegraph Com- 

 pany for information. He also takes pleasure in acknowledging the kindness 

 of Mv. T. F. Townsend, Signal Service Officer at Philadelphia, who has contrib- 

 uted his personal observations upon the aurora lor use in the present paper. 



