+---------------------------------------------+ | Year.| Number of | Days free | Days of | | | Groups. | from Spots.| Observation.| |---------------------------------------------| | 1826 | 118 | 22 | 277 | | 1827 | 161 | 2 | 273 | | 1828 | 225 | 0 | 282 | | 1829 | 199 | 0 | 244 | | 1830 | 190 | 1 | 217 | |---------------------------------------------| | 1831 | 149 | 3 | 239 | | 1832 | 84 | 49 | 270 | | 1833 | 33 | 139 | 267 | | 1834 | 51 | 120 | 273 | | 1835 | 173 | 18 | 244 | |---------------------------------------------| | 1836 | 272 | 0 | 200 | | 1837 | 333 | 0 | 168 | | 1838 | 282 | 0 | 202 | | 1839 | 162 | 0 | 205 | | 1840 | 152 | 3 | 263 | |---------------------------------------------| | 1841 | 102 | 15 | 283 | | 1842 | 68 | 64 | 307 | | 1843 | 34 | 149 | 324 | |(1844)| (52) | (111) | (320) | +---------------------------------------------+ "If we now compare together the number of groups, and the days free from spots, we find that the sun-spots have a period of about ten years, and that for about five years they are so numerous that during this period few days, if any, are free from spots. The sequel must show whether this period is constant, whether the minimum activity of the sun in producing spots lasts for one or two years, and whether this activity increases more quickly than it decreases." [Illustration: FEB. 18, 1894. FEB. 19, 1894. X.--PHOTOGRAPHS OF THE SUN TAKEN AT THE ROYAL OBSERVATORY, GREENWICH, SHEWING SUNSPOTS.] [Sidenote: Attracted little attention, until eight years later.] This brief announcement is all that the discoverer says upon the subject; and it is perhaps not remarkable that it attracted very little attention, especially when we remember that it related to a matter which the astronomical world had agreed to put aside as unprofitable and not worth attention. Next year, in giving his usual paper on the spots for 1844 he recurs to the subject in the following sentence: "The periodicity of spots of about ten years which was indicated in my summary published last year, is confirmed by this year's observations." I have added in brackets to the table above reproduced the numbers for 1844 subsequently given, and it will be seen how nearly they might have been predicted. [Sidenote: Other phenomena sympathetic and others not.]