NARRATIVE OF THE CRUISE. 
811 
be transformed either entirely or at the surface only into magnetic oxide, and in this 
latter case the nucleus is protected from further oxidation by the coating which thus 
covers it. 
“ One may suppose that meteorites in their passage through the atmosphere break 
into numerous fragments, that incandescent particles of iron are thrown off all round 
them, and that these eventually fall to the surface of the globe as almost impalpable 
dust, in the form of magnetic oxide of iron more or less completely fused. The luminous 
trains of falling stars are probably due to the combustion of these innumerable particles, 
resembling the sparks which fly from a ribbon of iron burnt in oxygen, or the particles of 
the same metal thrown off when striking a flint. It is easy to show that these particles 
in burning take a spherical form, and are surrounded by a layer of black magnetic oxide. 
“ Among the magnetic grains found in the same conditions as those just described 
are other spherules, which are referred to the chondres, so that if the interpretation of a 
Pig. 295. — Black Spherule 
with Metallic Nucleus (j). 
This spherule, covered with 
a coating of black shining 
magnetite, represents the 
most frequent shape. The 
depression here shown is 
often found at the surface 
of these spherules. Prom 
2375 fathoms, South Pacific. 
Pig. 296.— Black Spheral, 
with Metallic Nucleus ( § ”) ■ 
The black external coatin 
of magnetic oxide has been 
broken away to show the 
metallic nucleus, represented 
by the clear part at the. 
centre. Prom 3150 fathoms, 
Atlantic. 
cosmic origin for the magnetic spherules with a metallic centre were not established in a 
manner absolutely beyond question, it almost becomes so when their association with 
the silicate spherules is taken into account. It will be seen by the microscopic details 
that these spherules have quite the constitution and structure of chondres so frequent in 
meteorites of the most ordinary type, and on the other hand they have never been found, 
as far as is known, in rocks of a terrestrial origin ; in short, the presence of these 
spherules in the deep-sea deposits, and their association with the metallic spherules, is a 
matter of prime importance. 
“ Among the fragments attracted by the magnet in deep-sea deposits granules are 
distinguished slightly larger than the spherules with the shining black coating above 
described. These are yellowish brown, with a bronze-like lustre, and under the 
microscope, it is noticed that the surface, instead of being quite smooth, is grooved by 
thin lamellae. In size they never exceed a millimetre, generally they are about 0‘5 mm. 
