uld furnish on such hills the conspicuous points from which the fires
could be best seen. Let us suppose, then, that the rampart-crested
eminence of Knock Farril, seen on every side for many miles, has become
in the age of northern invasion one of the beacon-posts of the district,
and that large fires, abundantly supplied with fuel by the woods of a
forest-covered country, and blown at times into intense heat by the
strong winds so frequent in that upper stratum of air into which the
summit penetrates, have been kindled some six or eight times on some
prominent point of the rampart, raised, mayhap, many centuries before.
At first the heat has failed to tell on the stubborn quartz and feldspar
which forms the preponderating material of the gneisses, granites,
quartz rocks, and coarse conglomerate sandstones on which it has been
brought to operate; but each fire throws down into the interstices a
considerable amount of the fixed salt of the wood, till at length the
heap has become charged with a strong flux; and then one powerful fire
more, fanned to a white heat by a keen, dry breeze, reduces the whole
into a semi-fluid mass. The same effects have been produced on the
materials of the rampart by the beacon-fires and the alkali, that were
produced, according to Pliny, by the fires and the soda of the
Phoenician merchants storm-bound on the sands of the river Belus. But
the state of civilization in Scotland at the time is not such as to
permit of the discovery being followed up by similar results. The
semi-savage guardians of the beacon wonder at the _accident_, as they
well may; but those happy accidents in which the higher order of
discoveries originate occur in only the ages of cultivated minds; and so
they do not acquire from it the art of manufacturing glass. It could not
fail being perceived, however, by intellects at all human, that the
consolidation which the fires of one week, or month, or year, as the
case happened, had effected on one portion of the wall, might be
produced by the fires of another week, or month, or year, on another
portion of it; that, in short, a loose incoherent rampart, easy of
demolition, might be converted, through the newly-discovered process,
into a rampart as solid and indestructible as the rock on which it
rested. And so, in course of time, simply by shifting the beacon-fires,
and bringing them to bear in succession on every part of the wall, Knock
Farril, with many a similar eminence in