400 COSMOS. 



appearance of " narben." I think it preferable to designate 

 all the brighter portions of the Sun as luminous clouds, 

 dividing them, according to their form, into globate and 

 vein-like. These luminous clouds are irregularly distributed 

 over the Sun, and when more strongly manifested occasion- 

 ally impart a mottled or marbled appearance to the disc. 

 This is often distinctly visible over the entire circumference 

 of the Sun, and sometimes even to its poles, but yet always 

 most decidedly manifested in the two proper zones of the 

 spots, even when no spots are visible in those regions. At 

 such times these bright zones of Sun-spots vividly remind 

 one of Jupiter's belts. 



" The fainter portions lying between the vein-like luminous 

 clouds on the general surface of the Sun are deeper inden- 

 tations, and always present a shagreen-like grey, sand- like 

 appearance, reminding the observer of a mass of uniformly- 

 sized grains of sand. On this shagreen-like surface we may 

 occasionally notice exceedingly small faint grey (not black) 

 pores, which are further intersected by very delicate dark 

 veins. (Astr. Nachr. no. 473, p. 286.) These pores, when 

 present in large masses, form grey nebulous groups, consti- 

 tuting the penumbrae of the Sun-spots. Here the pores and 

 black points may be seen spreading from the nucleus to the 

 circumference of the penumbra, generally in a radiating form, 

 which occasions the identity of configuration so frequently 

 observed to exist between the penumbra and the nucleus." 



The signification and connection of these varying pheno- 

 mena can never be manifested in their entire importance to 

 the inquiring physicist, until an uninterrupted series of 

 representations of the Sun's spots 38 can be obtained by the 

 aid of mechanical clock-work and photographic apparatus, 

 as the result of prolonged observations during the many 



3S Sir John Herschel, Observations at the Cape, p. 434. 



