56 ANNUAL RECORD OF SCIENCE AND INDUSTRY. 



being purely hydrogen, have nothing to do with these solar 

 spots. In consequence of this being a year of minimum of 

 solar spots and protuberances, Father Secchi thinks he finds 

 therein the explanation of Professor Langley's result, since 

 the latter gentleman has observed that at present there is 

 no difierence of temperature between the sun's equator and 

 its poles. 6 B, LXXX., 1273. 



THE SOLAE OBSERVATORY AT POTSDAM. 



Some account of the new German solar observatory estab- 

 lished at Potsdam, near Berlin, is given in Klein's Wochen- 

 schrift, from which we gather that this institution is situa- 

 ted upon a considerable elevation, and will consist of a group 

 of several isolated observing domes, each to contain its own 

 telescope. Of these domes, the southern one, having a tele- 

 scope of eleven inches aperture, will be devoted to spectrum 

 analysis, which observations will be applied also to the stars 

 as well as the sun. In another dome the heliograph will be 

 established, which will be devoted also to the photography 

 of the sun, and possibly of the moon and stars. The west- 

 ern dome will contain a telescope of eight inches aperture 

 for special investigations of sun spots and protuberances. 

 The eastern dome will contain the telescope of seventeen 

 feet focal length now employed by Professor Sporer for the 

 study of the protuberances. North of these domes will be 

 the principal building, devoted to optical, physical, and chem- 

 ical researches, and north of it will be rooms for the assist- 

 ants, micrometric apparatus, etc. Still north of this building 

 will be one containing a large tank of water, in whose cellar 

 magnetic apparatus will be established. 



At the depth of one hundred feet under the ground a space 

 will be provided for erecting a Zollner's horizontal pendulum. 

 Finally, the dwelling-houses are to be mentioned, which will 

 accommodate quite a number of observers and officials. In 

 connection with the prosecution of Professor Sporer's ob- 

 servations of sun spots and protuberances, it is stated that 

 one of the most brilliant protuberances recently appeared in 

 the polar region of the sun, where they are generally want- 

 ing. It shot forth in nineteen minutes, and indicated with 

 certainty the presence of a violent storm at that point. 

 Klehi's Woche?isch7'ift, 1815^249, 



