Feb., 1906. The Shelburne Meteorite. 13 



impact upon the earth. Borgstrom has calculated from the depth 

 of the hole which the meteorite made in the earth that the velocity 

 with which it struck was one of 515 feet (157 m.) per second.* 

 This is equal to the velocity which a body falling in a vacuum 

 would acquire in 4600 feet. 



The substance of the meteorite as a whole is fairly coherent, 

 crumbling slightly under pressure by the fingers, but only slightly. 

 It is sufficiently coherent to take a good polish. The specific gravity 

 of the meteorite was determined in three ways, the determinations 

 being made by Mr. H. W. Nichols. The first two determinations 

 were made with a view to finding the apparent specific gravity, by 

 which the porosity of the stone is shown. This determination was 

 made in two ways. First, a cast of the meteorite was im- 

 mersed in a vessel full of water, and the weight of the water thus 

 displaced compared with that of the meteorite. This gave G = 3.288. 

 For the second determination the volume of the meteorite was deter- 

 mined by comparing the weight of a cube of unit size made of the 

 same plaster as the cast with the weight of the cast. The weight 

 of an equal volume of water compared with the weight of the mete- 

 orite gave G= 3.278. The third determination was made by the 

 ordinary method of comparing the weight of a piece of the meteorite 

 immersed in water with the weight of the same in air. From a 

 slab of the meteorite weighing 480 grams and partially bordered 

 with crust, the specific gravity obtained by this method was G = 

 3.504. This corresponds almost exactly with the result obtained 

 by Borgstrom, which was G = 3.499. Comparison of a mean of the 

 two values for apparent specific gravity with the specific gravity 

 as determined by the ordinary method, shows, using the formula 

 given by Kingf the porosity of the meteorite to be 6.3 per cent. 



The interior of the meteorite is in color light ash-gray, flecked 

 with rusty -brown about the metallic grains, which are nickel-white 

 to brass or bronze-yellow. Numerous circular spots of light and 

 dark gray color indicate chondri. Those of dark gray are generally 

 enstatite, those of light gray chrysolite. The diameter of the 

 chondri sometimes reaches 6 mm. The metallic grains are for 

 the most part rather uniform in size and distribution, appear- 

 ing as metallic points scarce exceeding 1 mm. in any dimension. 

 They may consist of nickel-iron alone, troilite alone or an aggregate of 

 these. The two compbnents may be readily distinguished by color. 



♦Op. cit.p. 75. 



t Agricultural Physics p. 115. 



