496 



SCIENCE 



[N. S. Vol. XLIX. No. 1273 



taxice. (This briglitness is of the order of 20 

 microlairiherts for a 24-inoh 75-ampere search- 

 lamp near by). The streaks appeared over a 

 region of the sky extending some 20 degrees to 

 either side of Polaris and from the horizon up 

 to Polaris and slightly higher. The individ- 

 ual streaks varied in -width from several de- 

 grees to a fractional part of a degree. There 

 were a few streamers that extended upward 

 very much farther than the others. These did 

 not lie symimetrieally with respect to Polaris 

 but to the eastward were more numerous. 

 Over these streaks of lighted sky as back- 

 ground appeared a wavering sheet of lighted 

 sky of lower brightness, whose undulations 

 seemed to travel from the horizon upward. 

 Wben the brightness of the streaks was great 

 enough the light was a decided green, other- 

 wise it appeared a faint greenish blue. 



The point of greatest brightness during this 

 display was a small patch of sky situated in 

 one of the streaks slightly to the eastward of 

 the vertical line passing through Polaris. This 

 patch was probably 2 degrees wide and very 

 much less in vertical thickness. Its distance 

 from the horizon was probably between 5 and 

 10 degrees. 



This gave an iexact semblance of a search- 

 light beam piercing a cloud. The brightness of 

 this patch was many times the brightness of the 

 streak in which it was situated, and was of a 

 very striking green color. We had hoped to 

 pihotograph this, but during the few moments 

 while the camera was being prepared it disap- 

 peared together with most of the streaks. The 

 streaks reappeared quite distinctly but this 

 bright patch did not. 



Other data which we chance to have on rec- 

 ord for other work are: 

 Temperature 11:45 p.m. 16° C. 

 Temperature recorded nearest the time of ap- 

 pearance of Aurora (2:50 a.m.) 15°. 

 Winds — practically none. 

 Sky — ^generally clear. 



Enoch Karrer, 

 E. P. T. Ttndall 

 BuKEAU OP Standards, 

 Washington, D. C, 

 May 9, 1919 



To THE Editor of Science : I have just come 

 in from viewing what to me was a remarkable 

 auroral display. Earlier in the evening, about 

 ten o'clock, while walking from a friend's 

 house, I saw the ordinary display of an arch of 

 light across the north with streamers extending 

 to a considera;ble height. This lasted for about 

 half an hour. Perhaps a quarter of an hour 

 after its disappearance I noticed a long band 

 or cloud of dim light across the sky which I at 

 first took to be an after-image on the retina. 

 But the image did not move with the eye, and 

 soon it became quite bright. This display ex- 

 tended from a point on the western horizon, 

 about 25° or 30° north of west, high up across 

 the sky over to a point on the eastern horizon 

 about 20° south of east. The band of light 

 widened as it left the horizon, at the highest 

 point being about 15° wide, extending from 

 declination 55° to about 70° declination. 



itfear the horizon the light was quite bright, 

 growing gradually dimmer as it slowly widened 

 out towards the highest point. At the westerly 

 end the south side of the band was cut ofE 

 sharply by a nearly vertical line. Elsewhere 

 the boundary was not very sharply drawn. In 

 about fifteen minutes the light began to fade, 

 but before entirely disappearing it brightened 

 up again nearly as bright as before. Soon 

 after, it faded again, entirely disappearing in 

 the upper portion. For fifteen minutes or so 

 the two ends remained, extending to a height 

 of about 45° from the horizon. The eastern 

 end broke into two parts as if cut in two. The 

 lower part shot up from the horizon like a 

 streamer, inclining a little to the south, the 

 sharp demarcation of the south side of the 

 western end persisted. The two ends remained 

 stationary during the entire time. At the sec- 

 ond maximum of brightness the upper part 

 moved farther north extending nearly to 

 Polaris. During the display none of the ordi- 

 nary auroral display across the northern hori- 

 zon was to be seen. If there was any it was 

 too faint to be seen in the vicinity of street 

 lights. 



I have seen a number of remarkable auroras 

 but have never before seen or heard of anything 

 like this one. The bright band of light extend- 



