henomena. It is evident that water played an important part
in these phenomena, though not as the prime mover;--any more than water
in the boiler of a locomotive is the prime mover in the generation of
the steam. Without the fuel in the furnace the steam would not be
produced; and the amount of steam generated will be proportional to the
quantity and heat of the fuel in the furnace and the quantity of water
in the boiler. In the case of Krakatoa, both these elements were
enormous and inexhaustible. The volcanic chimney (or system of
chimneys), being situated on an island, was readily accessible to the
waters of the ocean when fissures gave them access to the interior
molten matter. That such fissures were opened we may well believe. The
earthquakes which occurred at the beginning of May, and later on, on the
27th of that month, may indicate movements of the crust by which water
gained access. It appears that in May the only crater in a state of
activity was that of Perboewatan; in June another crater came into
action, connected with Danan in the centre of the island, and in August
a third burst forth. Thus there was progressive activity up to the
commencement of the grand eruption of the 26th of that month.[11] During
this last paroxysmal stage, the centre of the island gave way and sunk
down, when the waters of the ocean gained free access, and meeting with
the columns of molten matter rising from below originated the prodigious
masses of steam which rose into the air.

(_i._) _Cause of the Detonations._--The detonations which accompanied
the last great eruption are repeatedly referred to in all the accounts.
These may have been due, not only to the sudden explosions of steam
directly produced by the ocean water coming in contact with the molten
lava, but by dissociation of the vapour of water at the critical point
of temperature into its elements of oxygen and hydrogen; the reunion of
these elements at the required temperature would also result in
explosions.

The phenomena attending this great volcanic eruption, so carefully
tabulated and critically examined, will henceforth be referred to as
constituting an epoch in the history of volcanic action over the globe,
and be of immense value for reference and comparison.

[1] The eruption of Krakatoa has been the subject of an elaborate Report
published by the Royal Society, and is also described in a work by
Chevalier R. D. M. Verbeek, Ingenieur en Chef des Mines, and