ommander feared to continue his voyage and began
to shorten sail. From five to six o'clock a rain of pumice in large
pieces, quite warm, fell upon the ship, which was one of those that
escaped destruction during this terrible night.[6]

(_e._) _Electrical Phenomena._--During this eruption, electrical
phenomena of great splendour were observed. Captain Wooldbridge,
viewing the eruption in the afternoon of the 26th from a distance of
forty miles, speaks of a great vapour-cloud looking like an immense wall
being momentarily lighted up "by bursts of forked lightning like large
serpents rushing through the air. After sunset this dark wall resembled
a blood-red curtain, with edges of all shades of yellow, the whole of a
murky tinge, through which gleamed fierce flashes of lightning." As
Professor Judd observes, the abundant generation of atmospheric
electricity is a familiar phenomenon in all volcanic eruptions on a
grand scale. The steam-jets rushing through the orifices of the earth's
crust constitute an enormous hydro-electrical engine, and the friction
of the ejected materials striking against one another in their ascent
and descent also does much in the way of generating electricity.[7] It
has been estimated by several observers that the column of watery vapour
ascended to a height of from twelve to seventeen and even twenty-three
miles; and on reaching the upper strata of the atmosphere, it spread
itself out in a vast canopy resembling "the pine-tree" form of Vesuvian
eruptions; and throughout the long night of the 27th this canopy
continued to extend laterally, and the particles of dust which it
enclosed began to descend slowly through the air.

(_f._) _Formation of Waves._--This tremendous outburst of volcanic
forces, which to a greater or less extent influenced the entire surface
of the globe, gave rise to waves which traversed both air and ocean; and
in consequence of the large number of observatories scattered all over
the globe, and the excellence and delicacy of the instruments of
observation, we are put in possession of the remarkable results which
have been obtained from the collection of the observations in the hands
of competent specialists. The results are related _in extenso_ in the
Report of the Royal Society, illustrated by maps and diagrams, and are
worthy of careful study by those interested in terrestrial phenomena. A
brief summary is all that can be given here, but it will probably
suffice to bring h