METEOROLOGY OF THE SUN AND EARTH. 8i 



A third question is of geological interest. It has been asked whether 

 a study of the solar atraospliere may not throw some light upon the 

 peculiar constitution of the upper strata of the earth's surface, which 

 are known to be of less density than the average interior of our planet. 



If we have learned to be independent of total eclipses as far as the 

 lower portions of the solar atmosphere are concerned, it must be con- 

 fessed that as yet the upper portions the outworks of the sun can 

 only be successfully approached on these rare and precious occasions. 

 Thanks to the various government expeditions dispatched by Great 

 Britain, by the United States, and by several Continental nations 

 thanks, also, to the exertions of Lord Lindsay and other astronomers 

 we are in the possession of definite information regarding the solar 

 corona. 



In the first place, we are now absolutely certain that a large part 

 of this appendage unmistakably belongs to our luminary, and in the 

 next place, we know that it consists, in part at least, of an ignited gas 

 giving a peculiar spectrum, which we have not yet been able to iden- 

 tify with that of any known element. The temptation is great to as- 

 sociate this spectrum with the presence of something lighter than 

 hydrogen, of the nature of which we are yet totally ignorant. 



A peculiar physical structure of the corona has likewise been sus- 

 pected. On the whole, we may say that this is the least known, while 

 it is perhaps the most interesting, region of solar research ; most as- 

 suredly it is well worthy of further investigation. 



If we now turn our attention to matters nearer home, we find that 

 there is a difficulty in grasping the facts of terrestrial meteorology no 

 less formidable than that which assails us when we investigate solar 

 outbreaks. The latter perplex us because the sun is so far away, and 

 because also his conditions are so dilFerent from those with which we 

 are here familiar; while, on the other hand, the former perplex us be- 

 cause we are so intimately mixed up with them in our daily lives and 

 actions ; because, in fact, the scale is so large and we ai'e so near. 

 The result has been that until quite recently our meteorological opera- 

 tions have been conducted by a band of isolated volunteers individu- 

 ally capable and skillful, but from their very isolation incapable of 

 combining together with advantage to prosecute a scientific campaign. 

 Of late, however, we haA'e begun to perceive that, if we are to make 

 any advance in this very interesting and practical subject, a difierent 

 method must be pursued, and we have already reaped the first fruits 

 of a more enlightened policy ; already we have gained some knowledge 

 of the constitution and habits of our atmosphere. 



The researches of Wells and Tyndall have thrown much light on 

 the cause of dew. Humboldt, Dove, Buys Ballot, Jelinek, Quetelet, 

 Hansteen, Kupfier, Forbes, Welsh, Glaisher, and others, have done 

 much to give us an accurate knowledge of the distribution of terrestrial 

 temperature. Great attention has likewise been given to the rainfall 



VOL. Till. 6 



