123 



with the advantage of the fresh generation of heat which 

 takes place on the sudden stoppage by impact on the earth, 

 meteorites are sometimes so cold that they cannot be handled 

 immediately after their fall. This was the case with the 

 Dhurmsala meteorite of July 14, 1860 (284 W). 



As a matter of fact, meteorites are invariably found to be 

 covered with a crust or varnish, the thinness of which shows 

 the slight depth to which the heat has had time to penetrate. 

 The appearance of this crust varies according to the mineral 

 constitution of the meteorites : it is generally black as in 

 Wold Cottage (149 Z), often a shiny black, as in Stannern 

 (165 X), and sometimes of a grey colour, as in Durala (182 0). 



In the case of the Pultusk meteorite of January 30, 1868 

 (313 V), several thousands of stones, varying from the size 

 of an orange to that of a nut, were picked up, each covered 

 with a crust. In the Museum of Stockholm there are perfect 

 little meteorites covered with crust, which weigh no more than 

 a single grain ; they were gathered out of the snow after the 

 Hessle fall of January 1, 1869 (322 Y). 



The crust is not of equal thickness over the whole of the 

 meteorite, but, owing to the motion through the air, is gene- 

 rally in ridges and furrows, of which the directions indicate 

 the position of the meteorite in regard to its line of motion 

 at a certain part of its course ; and this relation is rendered 

 more clear by the position of the swellings produced by the 

 flow of the liquid material to the back of the moving mass. 

 Meunier grants that this crust is due to the action of heat, 

 but considers that the action is direct, and not through 

 fusion : he holds that only the outer surface of the crust itself 

 has been melted and that the furrows and swellings are due 

 to the scooping action of the air through which the meteorite 

 at first rushes with so enormous a velocity. The Nedagolla 

 iron (106 J) and the Goalpara stone (312 Y) illustrate this 

 peculiarity. 



Farther, the surface of a meteorite is generally covered 

 with r pittings which have been compared to thumb-marks ; 

 the Parnallee (265 NZ), and the Pultusk (313 Y) present 

 good examples of this character. It is remarkable that 

 pittings bearing a close resemblance to those of meteorites 



K 



