A. MATHEMATICS AND ASTRONOMY. 5 



Janssen did, but the green line was much fainter than he had 

 expected. He glanced at the corona through a six-inch tel- 

 escope. Its structure was exquisite and strongly developed. 



"I at once exclaimed, ' Like Orion!' Thousands of inter- 

 lacing filaments, varying in intensity, were visible ; in fact, I 

 saw an extension of the prominence structure in cooler mate- 

 rial. This died out some 5' or 6' from the sun, and then there 

 was nothing." 



Both Mr. Lockyer and Professor Respighi, of Rome, ob- 

 served the corona and chromosphere through a telescope 

 without a slit, as proposed by Professor Young. Thus four 

 images, one corresponding to each of the principal lines, were 

 distinctly seen, and the effect is described as very beautiful, 

 though nothing especially new was brought out. 



Several observers tried to reproduce Professor Young's ob- 

 servation of the reversal of all the lines of the spectrum at 

 the moment when the sun was just covered, but Major Ten- 

 nant, so far as we have yet heard, was the only one who suc- 

 ceeded. 



SECCIII ON SOLAR PROTUBERANCES AND SPOTS. 



Professor Secchi, the well-known astronomer, who has de- 

 voted a great deal of his time for some years past to the study 

 of the sun and its phenomena, communicates to the Academy 

 of Sciences a summary of his observations for the year 1871. 

 As general conclusions he remarks, first, that during the pe- 

 riod mentioned the law has been confirmed that the maxi- 

 mum of solar protuberances corresponds, in the region of the 

 spots, to a feeble minimum in relation to the equator. The 

 maximum in reference to the polar zones is scarcely sensible. 

 Second, in the field in question a habitual absence of polar 

 prominences w T as observed, these being only replaced by very 

 sensible elevations of the chromosphere. Third, with refer- 

 ence to protuberances, the height of which attains or surpass- 

 es five units, or forty seconds, these were found to be very 

 rare near the poles. Fourth, this absence of polar protuber- 

 ances is in harmony with the appearance of the granulations, 

 and of more brilliant bands, circumscribing the polar zones 

 of the sun, which are now very difficult to recognize, while 

 during the past year they were very visible. Fifth, the in- 

 tensity and number of the faculse have also diminished. Sixth, 



