28 KANSAS CITY REVIEW OF SCIENCE. 



Bootes is the next constellation east of Coma Berenices. It is marked by the 

 bright star Arcturus, which is of a reddish color. 



Corona Borealis, the northern crown, is the next east of Bootes. It is com. 

 posed of a pretty semi-circle of stars in the shape of a crown. 



INTERESTING FACTS CONCERNING THE SUN. 



Photography has proved an invaluable aid in the study of solar physics. By 

 its help astromomers now obtain pictures of sun spots accurate in all their details, 

 of the different phases of eclipses, and of phenomena of too short duration for 

 the eye to fully appreciate. At the observatory of the Roman College, Rome, 

 Italy, the late Father Secchi was accustomed to photograph the sun daily by 

 means of an instrument invented by himself; and having carried on this oper- 

 ation for several years, he possessed a record of occurrences on the solar surface 

 which has served as the basis of many important conclusions regarding our lumin- 

 ary. By comparing these pictures the periodicity of the spots has been deter- 

 mined ; and from data thus obtained, astronomers have reached the belief that 

 the sun acts not merely as a center of attraction and luminous source, but that it 

 exercises a potent effect on magnetic phenomena. 



The depth of the immense cavities forming the spots is usually about one- 

 third the earth's diameter, and never exceeds 4 000 miles. The cavities are by 

 no means empty, as the resistance which they offer to the passage of luminous 

 currents show that they are filled with more or less transparent vapors. They 

 are produced in the. luminous exterior of the sun — the photosphere — and are 

 craters therein^ filled with dark vapors which cut off the light from the lower 

 strata. They are the result of violeat crises in the interior of the solar globe, 

 which sometimes take place over large areas with great rapidity ; at other times 

 they occur quite slowly, last for a considerable period, and are seemingly inter- 

 mittent in their violence. The material which composes the penumbra of the spots, 

 and the cloudy bridges which cross or float over the dark portion, are masses of 

 photospheric matter. These masses are the result of violent action taking place 

 occasionally in the interior of the sun. Sometimes these actions are sudden ; at 

 others they take place slowly, and sometimes their action is renewed from time to 

 time ; and the interior trouble, of which they are but the manifestation, perseveres 

 for a long period after their first appearances. In fact, in a great number of in- 

 stances, there is a movement constantly going on, from the interior to the exterior 

 of the sun, and this movement is shown to us by the upheaval and the projection 

 of the luminous matter, the latter becoming visible under the form known to us as 

 facula. But generally, if we study the luminous masses which are seen as spots, 

 we find that they are comparable to vaporous clouds suspended in transparent 

 medium. The currents and the particles of the photosphere are driven toward 

 the center of the spots, where they dissolve and cease to be luminous. They are 



