relative extent of solar spots in each year. This table is generally employed as the basis of the calculations just referred to. Wolf's numbers, indicating the relative values of the sunspots observed in the different years of the present century. NOTE.-The values for the years 1800 to 1865 are from the 'Astronomische Mittheilungen,' von Dr. Rudolf Wolf, No. L. for February 1880. Those from 1866 to 1881 from the Astronomische Mittheilungen,' No. LV. April 1882. The maximum years are shown in Egyptian figures, thus (731). The minimum years in sloping figures, thus (1.8). ISOTHERMAL LINES SHOWING THE MEAN TEMPERATURE OF THE GLOBE FOR THE YEAR. The lines for 32° and below it are in blue. |