OBSERVATIONS OF LUMINOUS METEORS. 255 



chiefly from the pcu of Dr. Flight*, of aualyses and mineralogical examina- 

 tions during the past year of a great number and variety of meteoric products. 

 In addition to those above described of the meteorites of Orvinio, Roda, 

 Lodran, Adarc, and of several meteoric irons, the leading particulars of which 

 are given, some recent observations by Nordenskjold on snow-dust gathered 

 from the neves of various climates are noticed, with its probable relation to 

 meteor-dust in the atmosphere and to the blue colour of glacier -ice. The 

 whole of these short abstracts, occupying several pages of the printed volume, 

 arc full of concise and itseful information on the advance and progress which 

 have been made in the various departments of meteoric mineralogy during 

 the brief interval of the past year. 



A speculative paper on the origin of meteorites by Dr. G. Tschermakf 

 expresses very clearly the author's views on the present aspects of knowledge 

 regarding their history, and presents a number of important remarks on their 

 formation. The spectroscope has conhrraed the earlier conjectures, derived 

 from a study of meteorites, of a prevailing similarity of materials in the che- 

 mical elements of the hcavcnty bodies ; and from the forms of meteorites it may 

 be expected that a knowledge of the processes to which they have been sub- 

 jected may be derived. Apart from their minute internal structure, it is 

 certain that externally thc}^ are acutely angular fragments, evidently of a 

 large planetary mass, and (as shown by the crystalline structure of meteoric 

 irons and by sliding faces in some aerolites) of a large cosmical body where 

 uniform temperature and long periods of tranquillity have prevailed. Their 

 internal structure, exactly analogous to that of our volcanic tufas, is another 

 evidence of the same conclusion ; and Daubree regards collisions or explosions 

 of such large cosmical bodies as the origin from which they sprang. But as 

 their proportions are always diminutive or dust-like in comparison to the parent- 

 l)odies, explosive rather than disruptive agencies, or projectile forces acting 

 from within outwards locally upon the bodies, appear to have ushered their 

 ejected fragments into cosmical revolutions. With regard to their internal 

 structure, a further acquaintance with these " star-masses " before their dis- 

 integration is afforded to us by a close examination. Their porous materials, 

 made up of pulverized rocks, were correctly pronounced by Haidinger to be 

 volcanic products, which may be characterized as meteoric tuffs. Spherular 

 forms are of widely sjiread occurrenc* among their triturated grains, quite 

 round and unconformably crystallized with regard to their figure, when the 

 materials are tough, and varying in size from microscopic dust to that of small 

 bird-shot or milbt-seeds ; round fragments as large as a cherry are of rare 

 occurrence ; but in the volcanic rocks of our globe they ordinarily occur in 

 sizes varying from that of a hazel-nut to that of a bead. Kumberless small 

 volcanic fissures, it may be conjectured, contribute to their ejection ; and in no 

 meteorites do we trace the appearance of slag-like rock enclosing well-deve- 

 loped crystals which their formation from lava would lead us to expect. An 

 example of a true crater of explosion without ejection of lava is furnished by 

 the Eifel ; and in planetary bodies, where evolutions of occluded gases play a 

 prominent part in the disturl)ances of the surface, the projection of such frag- 

 ments as we find in meteorites from active volcanic craters may not be an 

 unnatural or altogether improbable hypothesis of the kind of action of phy- 

 sical forces concerned in their formation, 



* ' The Geological Record for 1874 : an account of Works on Geology, Mineralogy, and 

 Pala-ontology published during the Year.' Article " Petrology," p. 21(3. London : Taylor 

 and FranciB, 1875. 



t " Die Bildung der Meteorite)!, and i\or Vulkauisraus," Vienna Acad. Sitzungsbericlite, 

 187.5, pt. ii. April 187."). 



