A. MATHEMATICS AND ASTRONOMY. 49 



theory upon the nature and cause of the aurora rather 

 must we still further diligently observe and establish the 

 regularity of the phenomena. 19 (7, 18V3, 234. 



THE RED FLAMES OF THE SUJ^^ SEEN WITH A COMMON TEL- 

 ESCOPE. 



Mr. R. Langdon communicates to Nature the result of 

 some observations which are well worthy of being repeated. 

 Very few observers have met with such success in this line 

 as he appears to have had, and his method will place it with- 

 in the power of the amateur every where, at very little ex- 

 pense, to observe the red protuberances of the sun. Langdon 

 states that he cut out several circular disks of thin brass, 

 blackened on both sides, and, after trying several, found one 

 the right size, such that when inserted in the interior of his 

 telescope at the focus of the object-glass, it very exactly con- 

 cealed the glowing body of the sun. He expected then, pos- 

 sibly, to be able to view the protuberances on the limb of the 

 sun, and in this he states that he was successful, so that on 

 the 16th of June, 1872, he observed such a protuberance on 

 the southwestern limb of the sun, and on the 20th of Septem- 

 ber he again saw a red flame. These flames did not appear 

 to be projected against the sky, but upon a very delicate pur- 

 ple background. No colored glass was used in either of 

 these observations, but while adjusting the apparatus a sheet 

 of letter paper was held betw^een the eye and the telescope, 

 which was removed the instant the sun w^as exactly behind 

 the artificial occulting disk. This method reminds one of a 

 proposition recently made by Professor Abbe to Dr. John W. 

 Draper, of New York, in which it was projDOsed to place at 

 the solar focus a plate of glass having a central circular aper- 

 ture equal to the diameter of the solar image : the light and 

 heat of the solar disk passes through the aperture, while by 

 using properly selected chemicals we should be able to di- 

 rectly photograph the solar protuberances without waiting 

 for a total eclipse of the sun. 12 -4, 1873, 263. 



ASTEROID NO. 134. 



Professor Henry has received a telegram from Professor 

 Foerster, Director of the Berlin Observatory, announcing the 

 discovery by Dr. Luther, at Dusseldorf, of a planet on the 



C 



