ASTRONOMY AND METEOROLOGY. 311 







the polariscope next December, since if there were but two the 

 result would probably be contradictory, as was the case with re- 

 gard to the observations made in India, in 1868, and in America 

 last year. Different parts of the corona ought also to be exam- 

 ined. Nature. 



SOLAR PROTUBERANCES. 



The following is a communication to the editor of the " Journal 

 of the Franklin Institute " (Professor Morton) from Professor 

 Young of Dartmouth College : 



"I write to inform you that last Thursday, Sept. 22d, about 11 

 A.M. Hanover mean time, I was so fortunate as to see the 

 sodium lines D X and D 2 reversed in the spectrum of the umbra of 

 a large spot near the eastern limb of the sun. At the same time 

 the c. and F. lines were also reversed, but with the great disper- 

 sive power of my new spectroscope I see this so often in the solar 

 spots, that it has ceased to be remarkable. 



" I am not aware that this reversal of the sodium lines in a spot 

 spectrum has ever been observed before ; its reversal in the spec- 

 tra of prominences is not very unusual. A small prominence on 

 the western limb of the sun, which was visible the same forenoon, 

 presented all the following bright lines, namely, c, D t , D 2 , D 3 , 

 1474, fcj.&a, 6 4 , 1989.5, 2001.5, 2031., r, 2581.5, 2796., and h; 

 15 in all. 



" In the spot spectrum the magnesium lines 6 t , 6 2 , and 6 4 , were 

 not reversed, but while the shade which accompanies the lines 

 was perceptibly widened, the central black line itself was thinned 

 and lightened." 



SPECTRUM OF A SOLAR PROMINENCE. 



Professor Young, of America, has made a remarkable observa- 

 tion. On April 9, 1870, there was an exceedingly bright promi- 

 nence on the south-west limb of the sun, near, but not over, a 

 large spot which was passing off. At the base of this prominence, 

 which was shaped like a double ostrich-plume, the C line was in- 

 tensely brilliant, so that the slit could be opened to its whole width 

 in studj'ing the form of the prominence, but this line was not in 

 the least distorted. On the other hand the F line, also very bril- 

 liant, was shattered all to pieces, so that at its base it was 3 or 4 

 times as wide as it ordinarily is, and several portions were en- 

 tirely detached from the rest. This is a most perplexing result, 

 and seems to throw doubt on the interpretation which has hitherto 

 been given to the displacement of the solar spectral lines. As 

 Professor Young remarks, " Since the C line was not similarly 

 affected, it is hardly possible to attribute this breaking up of F to 

 cyclonic motions in the gas from which the light emanates, and it 

 becomes very difficult to imagine a cause that can thus disturb a 

 single line of the spectrum itself." "Possibly," he adds, but we 

 must admit we can hardly conceive the possibility, "the appear- 

 ance may be the result of local absorptions acting upon a line 



