42 ANNUAL RECORD OF SCIENCE AND INDUSTRY. 



rical parts. Seventh, it also results that the mean accumu- 

 lation which is produced at the extremities of the diameter 

 of the photosphere takes place instantly by preference in the 

 northern hemisphere. Eighth, it seems, then, probable that 

 a larger quantity of the gaseous mass may be suspended in 

 the northern than in the southern hemisphere. It must be 

 that this accumulation occasions the excess of temperature 

 in the northern hemisphere, and opposes therein some re- 

 sistance to the manifestation of the interior activity of the 

 sun. Father Rosa finally concludes that the secular varia- 

 tions of the photosphere and of terrestrial magnetism are 

 simultaneous, and subjected to an oscillation of 66| years, 

 similar to that which the apogee of the apparent orbit of the 

 sun is subject to. We can thus consider our sun as making 

 a part of a triple stellar system, in which the interior star 

 combines with our sun in a movement about the same centre, 

 whose period is 66f years. Biblioth. U?iivers., 1874, 259. 



SOLAR RADIATION IX EGYPT. 



M. Picte has communicated several series of observations 

 which he has had occasion to make during a prolonged sojourn 

 at Cairo, as director of the Physical Cabinet of that city, and 

 amono; them he has made some measurements of solar radia- 

 lion with a large actinometer. His apparatus consisted of 

 a sort of boiler, of two thin plates of parallel sheet iron, filled 

 with water, placed in a chest full of black cotton, and closed 

 over its face, which was turned toward the sun, by a compar- 

 able number of plates of glass. As a result he finds that, in 

 Egypt, a surface of one square meter exposed normally to the 

 rays of the sun in the middle of the day absorbs very nearly 

 twelve calories or units of heat per minute. Other observ- 

 ers, also operating in Egypt, have found about ten calories. 

 The diurnal evaporation produced by the action of the sun 

 is one sixth of an inch of water. The evaporation which is 

 due to the dryness of the air and to the wind is one third of 

 an inch. Uiblioth. Univers., 1874, 484. 



THERMOGRAPHS OF THE ISOTHERMAL LINES OF THE SOLAR 



DISK. 



Professor Mayer announces that he has devised a method 

 for obtaining the isothermals on the solar disk, by which in- 



