FEB., 1906. THE SHELBURNE METEORITE. 13 
impact upon the earth. Borgstroém 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 Borgstrém, 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 Kingy 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 ale ie or an aggregate of 
these. The two compdnents may be readily di.tinguished by color. 
FOp cit. p. 75. j 
7 Agricultural Physics p. 115. 
