eet.

This quantity of mud would in one year raise a surface of 228-1/2 square
miles, or a square space, each side of which should measure 15 miles, a
height of one foot. To give some idea of the magnitude of this result,
we will assume that the specific gravity of the dried mud is only
one-half that of granite (it would, however, be more); in that case, the
earthy matter discharged in a year would equal 3,184,038,720 cubic feet
of granite. Now about 12-1/2 cubic feet of granite weigh one ton; and it
is computed that the great Pyramid of Egypt, if it were a solid mass of
granite, would weigh about 600,000,000 tons. The mass of matter,
therefore, carried down annually would, according to this estimate, more
than equal in weight and bulk forty-two of the great pyramids of Egypt,
and that borne down in the four months of the rains would equal forty
pyramids. But if, without any conjecture as to what may have been the
specific gravity of the mud, we attend merely to the weight of solid
matter actually proved by Mr. Everest to have been contained in the
water, we find that the number of tons weight which passed down in the
122 days of the rainy season was 339,413,760, which would give the
weight of fifty-six pyramids and a half; and in the whole year
355,361,464 tons, or nearly the weight of sixty pyramids.

The base of the great Pyramid of Egypt covers eleven acres, and its
perpendicular height is about five hundred feet. It is scarcely possible
to present any picture to the mind which will convey an adequate
conception of the mighty scale of this operation, so tranquilly and
almost insensibly carried on by the Ganges, as it glides through its
alluvial plain, even at a distance of 500 miles from the sea. It may,
however, be stated, that if a fleet of more than eighty Indiamen, each
freighted with about 1400 tons' weight of mud, were to sail down the
river every hour of every day and night for four months continuously,
they would only transport from the higher country to the sea a mass of
solid matter equal to that borne down by the Ganges, even in this part
of its course, in the four months of the flood season. Or the exertions
of a fleet of about 2000 such ships going down daily with the same
burden, and discharging it into the gulf, would be no more than
equivalent to the operations of the great river.

The most voluminous current of lava which has flowed from Etna within
historical times was that of 1669. Ferrara, afte