600 REPORT— 1886. 



features wlaich cannot be discovered in the Neumann lines, grade into the latter by- 

 such insensible steps that no natural division can be made between the two classes 

 of phenomena. It is shown also that the plates, of which both the figures and the 

 lines referred to are sections, are always parallel to faces of one of the three 

 fundamental forms of the regular system, the octahedron, dodecahedron, and cube, 

 and that the complications observed are only due to twinning. Figures were 

 drawn illustrating these points, and representing Widmanstattian plates in all the 

 positions described. 



It is further shown that the planes of fracture frequently observed in the iron 

 meteorites are also parallel to the faces of the same three fundamental forms. 

 Such fractures have, in most cases, resulted from the concussion produced by the 

 rapid passage of the meteorite through the air, but may also at times be obtained 

 artificially, and ditfer in no respect from true cleavage planes, except in so far as 

 the malleaioility of the metal prevents us from developing the cleavage in the usual 

 way. This cleavage is distinguished from the jointed structure, sometimes result- 

 ing from the segregation of impurities and corresponding to the Widmanstattian 

 figures. It appears markedly in some of the most compact meteorites, and often 

 crosses the Widmanstattian plates. Finally, the close agreement of these phenomena 

 with what has been observed in the artificial crystallisation of iron and other 

 materials is pointed out. 



This investigation throws no new light upon the origin of meteorites, except so 

 far as it strengthens the opinion that the process of crystallisation must have been 

 extremely slow. The occurrence of large masses of native iron occluding hydrogen 

 gas, and containing nickel, cobalt, phosphorus, sulphur, &c., implies a combination 

 of conditions which the spectroscope indicates as actually realised in our own sun 

 and in other suns among the fixed stars, and the most probable theory seems to be 

 that these masses were thrown off from such a sun, and that they very slowly 

 cooled, while revolving in a zone of intense heat. 



