94 REPORT — 1859. 



slightly excentric with regard to the sun, so that the earth passes through its 

 extremity once in its revolution, about Nov. 12. — [Edinb. Trans.] 



Chladni conceives innumerable small bodies revolving in the solar system, 

 and subject to the laws of gravitation. Messier, in 1777 (Memoirs of Royal 

 Acad. Paris, 1777, p- 464), has recorded "Observation singulier d'une pro- 

 digieuse quantite de petites globules qui ont passe au devant du disque du 

 soleil." Mr. Rumker has more recently recalled the attention of astrono- 

 mers to the subject. 



Some supposed analogous phenomena are not perhaps really entitled to be 

 so considered ; yet they tend to support the fact that diffuse matter of kinds 

 little known may exist. 



Such instances are those of dry fogs occasionally observed. The most re- 

 markable on record is, perhaps, that of 1783; a remarkable year, in which, 

 besides this phenomenon, there occurred a great volcanic eruption of Hecla, 

 earthquakes in Calabria, and the passage of one of the largest and most re- 

 markable meteors ever witnessed, and seen all over England. 



The fog occurred over a great part of Europe, the north of Africa, and 

 North America ; but not in the middle of the Atlantic, perhaps owing to 

 some current of the atmosphere which partially cleared it away. It continued 

 more than a month. In some places it was observed to obscure or redden 

 the sun ; yet in general the stars were seen through it. It was accompanied 

 by an unpleasant smell, was perfectly free from moisture, not affecting the 

 hygrometer, and exhibited a. phosphorescence. 



It has been argued that its long continuance precludes the idea of its 

 being the tail of a comet ; but this is no proof that it might not have been 

 a portion detached from such a nebulous mass, and retained by the earth till 

 condensed or dissipated : whether it could be connected with the volcanic 

 eruption, or with the meteor, remain questions open to speculation. 



In 1831 a similar phenomenon was observed on the African coast, N. Ame- 

 rica, and Asia Minor, as well as in France and some other parts of Europe. 

 The sun is said to have appeared blue through it ; but the stars were occa- 

 sionally obscured. These phenomena, however, may be purely terrestrial ; as 

 the Harmattan, or blowing of dust from the African deserts over the Atlantic, 

 as well as the dust from volcanic eruptions, have been known to produce very 

 similar effects. 



In the catalogue originally given by Chladni (see Edinb. Phil. Journal, 

 No. II.), largely confirmed by later instances, we find full verification of the 

 fact, that meteoric matter has fallen of every degree of density, from the con- 

 dition of almost pure metal to that of ore or oxide, more or less earthy, to 

 matter of light, porous, soft or spongy nature, or even of the character of 

 fine dust, or a dry fog or haze floating in the atmosphere : though it must be 

 owned, the connexion of such phenomena as the last mentioned with those 

 of meteoric masses may not be sufficiently proved. 



["For some details in reference to this point, see Arago on the comet of 

 1833 (translation by Col. Gold); also ' Comptes Rendus,' 1847.] 



The student should not overlook the ingenious conclusion of Sir H. Davy 

 (Phil. Trans. 1817, Pt. I. p. 75), that the combustion of meteors must be 

 that of solid matter, since combustion of elastic fluids could not be supported 

 in so rarefied an atmosphere as exists at the great heights at which it occurs 

 even in those instances which fall within the limits of our atmosphere. 



One of the most instructive cases is that of a great meteor observed at the 

 Cape of Good Hope (Phil. Trans. 1839, Part I.) which was seen to burn 

 by daylight and to fall in portions, which were immediately collected and 

 examined. The most considerable part of it is preserved in this country. 



