long duration, as does the progress in the arts implied by the
rudeness of the earlier tools, often mere repetitions of those of
the stone age, as contrasted with the more skilfully worked weapons
of a later stage of the same period.

It has been suggested that an age of copper must always have
intervened between that of stone and bronze; but if so, the
interval seems to have been short in Europe, owing apparently to
the territory occupied by the aboriginal inhabitants having been
invaded and conquered by a people coming from the East, to whom the
use of swords, spears, and other weapons of bronze was familiar.
Hatchets, however, of copper have been found in the Danish peat.

The next stage of improvement, or that manifested by the
substitution of iron for bronze, indicates another stride in the
progress of the arts. Iron never presents itself, except in
meteorites, in a native state, so that to recognise its ores, and
then to separate the metal from its matrix, demands no
inconsiderable exercise of the powers of observation and invention.
To fuse the ore requires an intense heat, not to be obtained
without artificial appliances, such as pipes inflated by the human
breath, or bellows, or some other suitable machinery.

DANISH SHELL-MOUNDS, OR KJOKKENMODDING.*

(* Mr. John Lubbock published, after these sheets were written, an
able paper on the Danish "Shell-mounds" in the October number of
the "Natural History Review" 1861 page 489, in which he has
described the results of a recent visit to Denmark, made by him in
company with Mr. Busk.)