distinguished from logs of dark-coloured wood without their bark.

Many of the basaltic streams can be traced, either to points of eruption at
the base of the great central mass of trachyte, or to separate, conical,
red-coloured hills, which are scattered over the northern and western
borders of the island. Standing on the central eminence, I counted between
twenty and thirty of these cones of eruption. The greater number of them
had their truncated summits cut off obliquely, and they all sloped towards
the S.E., whence the trade-wind blows. (M. Lesson in the "Zoology of the
Voyage of the 'Coquille'" page 490 has observed this fact. Mr. Hennah
("Geolog. Proceedings" 1835 page 189) further remarks that the most
extensive beds of ashes at Ascension invariably occur on the leeward side
of the island.) This structure no doubt has been caused by the ejected
fragments and ashes being always blown, during eruptions, in greater
quantity towards one side than towards the other. M. Moreau de Jonnes has
made a similar observation with respect to the volcanic orifices in the
West Indian Islands.

VOLCANIC BOMBS.

(FIGURE 3: FRAGMENT OF A SPHERICAL VOLCANIC BOMB, with the interior parts
coarsely cellular, coated by a concentric layer of compact lava, and this
again by a crust of finely cellular rock.

FIGURE 4: VOLCANIC BOMB OF OBSIDIAN FROM AUSTRALIA. The upper figure gives
a front view; the lower a side view of the same object.)

These occur in great numbers strewed on the ground, and some of them lie at
considerable distances from any points of eruption. They vary in size from
that of an apple to that of a man's body; they are either spherical or