202 Description and Analysis of a Meteoric Stone. 



of the intervention of cloud between the spectator and the 

 sun, moon, or planet, the peculiar refraction of which causes 

 the appearance : but there is another well-known phaeno- 

 menon which aUvays appears in a cloud opposite to the sun 

 or moon, namely the 



Iris. Dcf. Circulus maximus coloralns immle soli op- 

 positd visus, (jui, quod portio ejus iantiim videaiur, 

 arcus apparent. 



Ol'ser. The rainbow is too familiar to every one to need 

 any particular description. 



Iris duplex. Def. Duo circuli maxlmi colorali^ quo- 

 rum centra communi sol oppositus est ; qui, quod eorum 

 portioves taiitiim videantur, arcus appareunt. 



Ohser. Irises or rainbows alwavs appear in the nimbus 

 when that cloud is pouring down rain from a situation op- 

 posite to the sun. 



Concernino; the cause of hnlones, &c. all that can be 

 said isj that these phjenomcna must depend on some pe- 

 culiar unexplored structure of the refracting cloud. I be- 

 lieve, always a cirroslra'wi, in cases of /lalo, parhcHon, and 

 paraselene; though a corona is sometimes seen in thin flimsy 

 confluent clrrocumulus. To me it appears that the angle 

 of the semidianieter of a halo must always correspond with 

 the aufflc at which the fays are refracted, as they must all 

 fall physically parallel on every part of the cloud. — For more 

 particulars relative to the structure of clouds refracting ibese 

 phasnomena I nmst refer your renders to Phil. Trans, vol. v. 

 1065; — xxii. 535; — xxxi. 21 -2 ;— xxxix. US; — xlvi. 19G; — 

 lii. 3 ; — M. Hclvetius, end ij'i'^- Merc. in Sole;"— D^s Carles's 

 Treatise of Meteors; — M. Huygens's Posth. Works, p.i'93j 

 and Newton's Oplic. 1st edit. p. 13-4'. 



Thovas Forster. 



XLVni. Descriplion and Analijsi'i of a Meteoric Stone 

 which fell in the County of Tipperary, in Ireland, in the 

 Month of August iQ\0. By William Higgins, Ey^. 



To Mr. rUlock. 



JDear Sin, /\s meteoric stones have lately engaged ll.e 

 attention of the philosophical world, perbhps the following 

 description and aualysisof a stone that had fdienlast August, 

 duriniT ^ thunder-storm, in the county of 'I'ippcrarv, in ire- 

 land, very i)ear the house of Maurice Crosbie Moore, esq. 

 will be acceptable to many of the numerous readers of your 

 very useful Journal. |t will at least add to tlje authenlicitv 

 • ■ of 



