“‘Il est manifest par ce que nous venons de rapporter qu’il n’y a point de règle certaine de leur formation, ni de leur nombre et de leur figure,’ says Cassini II. in 1740.—Elém d’Astron., vol. i. p. 82.

“‘Il semble qu’elles ne suivent aucune loi dans leur apparitions,’ says Le Monnier in 1746.—Instit. Astron., p. 83.

“‘Solar spots observe no regularity in their shape, magnitude, number, or in the time of their appearance or continuance,’ says Long in 1764.—Astron., vol. ii. p. 472.

“‘Les apparitions des tâches du soleil n’ont rien de regulier,’ says Lalande in 1771.—Astron., vol. iii. § 3131, 2nd edit.

“And Delambre’s opinion may be inferred from a well-known passage in the third volume of his ‘Astronomy’ (p. 20), published in 1814, where treating of the solar spots he says, ‘Il est vrai qu’elles sont plus curieuses que vraiment utiles.’”[4]

It will thus be evident that Herr Schwabe had the courage to enter upon a line of investigation which others had practically condemned as likely to lead nowhere, and that his discovery was quite contrary to expectation. It is a lesson to us that not even the most unlikely line of work is to be despised; for the outcome of Schwabe’s work was the first step in the whole series of discoveries which have gradually built up the modern science of Solar Physics, which occupies so deservedly large a part of the energies of, for instance, the great observatory attached to the University of Chicago.

Schwabe’s announcement.

It has been our practice to recall the actual words in which the discoverer himself stated his discovery, and I will give the original modest announcement of Schwabe, though for convenience of those who do not read German I will attempt a rough translation. He had communicated year by year the results of his daily counting of the solar spots to the Astronomische Nachrichten, and after he had given ten years’ results in this way he collected them together, but he made no remark on the curious sequence which they undoubtedly showed at that time. Waiting patiently six years for further material, in 1843 he ventured to make his definite announcement as follows:—“From my earlier observations, which I have communicated annually to this journal, there was manifest already a certain periodicity of sun-spots; and the probability of this being really the case is confirmed by this year’s results. Although I gave in volume 15 the total numbers of groups for the years 1826-1837, nevertheless I will repeat here a complete series of all my observations of sun-spots, giving not only the number of groups, but also the number of days of observation, and further the days when the sun was free from spots. The number of groups alone will not in itself give sufficient accuracy for determination of a period, since I have convinced myself that when there are a large number of sun-spots the number will be reckoned somewhat too small, and when few sun-spots, the number somewhat too large; in the first case several groups are often counted together in one, and in the second it is easy to divide a group made up of two component parts into two separate groups. This must be my excuse for repeating the early catalogue, as follows:—

Year.Number of
Groups.		Days free
from Spots.		Days of
Observation.
1826118 22277
1827161 2273
1828225 0282
1829199 0244
1830190 1217
1831149 3239
1832 84 49270
1833 33139267
1834 51120273
1835173 18244
1836272 0200
1837 33 0168
1838282 0202
1839162 0205
1840152 3263
1841102 15283
1842 68 64307
1843 34149324
(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.”