6k 



Tables 772-774 



TABLE 772.— The Solar Constant, 1930, 1931 



TABLE 773.— Wolf s Observed Sun-Spot Numbers. Annual Means 

 Sun-spot number = &(io X number of groups and single spots observed + total number of spots ir 

 groups and single spots), k depends on condition of observation and telescope, equaling unity for Wol: 

 with 3-in. telescope and power of 64. Wolf's numbers are closely proportional to spotted area on sun 

 100 corresponds to about 1/500 of visible disk covered (umbras and penumbras). Periodicity: mean 

 II. 13, extremes, 7.3 and 17. 1 years. Terr. Magn. 30, 83, 1925, monthly means 1749-1924. See A. Wolfei 

 in Astronomische Mitteilungen and Zeitschrift fur Meteorologie, daily and monthly values. See alsc 

 Bull, for Character Figures of Solar Phenomena, Int. Astron. Union, Eidgen, Zurich, for spots and othei 

 solar phenomena. Also, Terr. Magn. and Atm. Elec, 33, 223, 1928, for central spots, 1917 to 1927. 



Note — The sun's apparent magnitude is —26.5, sending the earth 90,000,000,000 times as much light 

 as the star Aldebaran. Its absolute magnitude is + 4.8. 



Ratio of total radiation of sun to that of moon about 100,000 to 1' 

 " light " 400,000 to 1 



Langley. 



Smithsonian Tables 



For more extensive table, see Smithsonian Meteorological Tables 



