612 



SCIENCE. 



[N. S. Vol. XVIII. No. 463. 



might exist between them and terrestrial 

 weather changes.* 



In the first year of the last century, Sir 

 Wm. Hersehel drew attention to this sub- 

 ject, f He wrote: 



Tlie first thing which appears from astronom- 

 ical observations of the sun is that the periods of 

 the disappearance of spots on the sun are of much 

 greater duration than those of their appearance. 



With regard to the contemporary severity and 

 mildness of the seasons, it will hardly be neces- 

 sary to remark that nothing decisive can be ob- 

 tained. An indirect source of information, how- 

 ever, is opened to us by applying to the influence 

 of sunbeams on the vegetation of wheat in this 

 country. I do not mean to say that this is a real 

 criterion of the quantity of light and heat- emitted 

 by the sun, much less will the price of this article 

 completely represent the scarcity or abundance 

 of the absolute produce of the country. 



On reviewing the period 1650-1713, it seems 

 probable, from the prevailing price of wheat, that 

 some temporary scarcity or defect of vegetation 

 has generally taken place when the sun has been 

 mthout those appearances which we surmise to 

 be symptoms of a copious emission of light and 

 heat. 



To those acquainted with agriculture who may 

 remark that wheat is well-known to grow in cli- 

 mates much colder than ours, and that a proper 

 distribution of rain and dry weather are probably 

 of much greater consequence than the absolute 

 quantity of light and heat derived from the sun, 

 I shall only suggest that those very circumstances 

 of proper alternations of rain and dry weather 

 and wind, etc., favorable to vegetation, may pos- 

 sibly depend on a certain quantity of sunbeams 

 being supplied to them. 



Herschel's suggestion was a daring one, 

 for however perfect our national statistics 

 may have been in relation to the price of 

 wheat, there was nowhere kept up a con- 

 tinuous record of the changes observable 

 on the sun's surface, nor had there been 

 any serious attempt made to determine the 

 law underlying them. 



In 1825 this serious attempt was made, 

 and by Schwabe of Dessau, who discovered 



* Blandford, Bengal, Asiat. Soc. Journ. 65; 

 Part II., 1875, p. 22. 



t Phil. Trans., 1801, p. 205. 



a cycle of about eleven years in the solar 

 changes. Wolf afterwards took up the 

 question. 



Hersehell had associated the variation in 

 the number of spots with that in the price 

 of corn, the connecting link being sunshine 

 or weather. It was to him a question of 

 meteorology. 



A year after the publication of Her- 

 schel's papers, WoUaston extended the 

 early spectrum work of Kepler and New- 

 ton by discovering that in the solar spec- 

 trum there were many dark lines; these 

 were for the first time mapped by Fraun- 

 hofer in 1814. 



Soon after 1850 it became a question of 

 the connection of sun spots with terrestrial 

 magnetism as weU as with meteorology. A 

 new idea was introduced. 



Lamont, Sabine and Allan Broun discov- 

 ered that there was a well marked coinci- 

 dence between the variations of magnetic 

 efi'ects, as observed on the surface of our 

 planet by delicately suspended magnets, 

 and the quantity of spotted area observed 

 on the sun. This in later telegraphic days 

 is not merely a pious opinion which does 

 not interest anybody, because, when the 

 magnetic changes are very considerable and 

 the disturbances arrive at a maximum, it. 

 is very difficult to get a telegram from 

 London to Brighton. 



The period around the year 1860 was 

 rendered ever memorable by a still further- 

 extension of Kepler's and Newton's work, 

 which at once explained the dark lines ob- 

 served in the solar spectrum by WoUaston 

 and Praunhofer. 



Hitherto iindreamt-of attacks on the na- 

 ture of the sun became possible. The- 

 names of Kirchhoff, Bunsen, Angstrom, 

 Stokes, Balfour Stewart will go for very 

 long down the stream of time, because 

 they showed us that in spectrum analysis 

 we had the power of practically conversing, 

 chemically, with the distant worlds in 



