A. MATHEMATICS AND ASTRONOMY. 7 



the temperature of the chromosphere, 49,850 Fahr. ; and for 

 the temperature of the interior region, whence the hydrogen 

 is erupted, 123,150 Fahr. Assuming the atmospheric press- 

 ure at the base of the chromosphere to be about equal to 

 seven inches of the mercurial barometer, he finds the pressure 

 at the level of the nuclei of the spots to be about 184,000 at- 

 mospheres, and the pressure in the inner region before named 

 no less than 4,070,000 atmospheres. 5 A, October, 1870, 419. 



CHARACTER OF SUN-SPOTS. 



According to a recent communication of Professor Zollner, 

 as given in JVature, " the sun-spots are slag-like by the radia- 

 tion of heat on the glowing and liquid surface of the sun, the 

 products of the cooling having again dissolved in consequence 

 of the disturbance of equilibrium produced by themselves in 

 the atmosphere. When these disturbances are not only lo- 

 cal, but generally distributed, the formation of new spots is 

 but little favored at the times of such general motion of the 

 atmosphere, because then the most essential conditions of the 

 surface are wanting for a severe depression of temperature 

 by radiation namely, the rest and clearness of the atmos- 

 phere. But when the surface has again gradually become 

 quiet after the dissolution of the spots, the process again re- 

 commences, and acquires in this manner aperiodic character, 

 in consequence of the mean relationships of the surface of the 

 sun, which may be considered as attaining an average in long 

 periods. The distribution of the spots in area must, accord- 

 ing to this theory, be determined by the zones of the greatest 

 atmospheric clearness, which, as has been shown, generally 

 coincide with the zones of the greatest abundance of spots." 

 \1 A.March 16,1871,393. 



COINCIDENCE OF THERMOMETRY AND SUN-SPOT CURVES. 



Mr. Stone, the astronomer royal at the Cape of Good Hope, 

 in comparing the thermometric curves taken at the Cape 

 since 1841 with those in Wolf's observations on the sun- 

 spots, finds an agreement between the two series so close as 

 to induce him to think that the same cause which leads to 

 the excess of mean annual temperature leads equally to a 

 dissipation of solar spots, and also that there is an approxi- 

 mately decennial period of such temperature. He leans, how- 



