n had forsaken the forests
and glens of Germany, they dwelt in their palaces deep in the Harz
Mountains, in the Dwarfholes, &c., whence they came from time to time
into the upper air.

The Seven Sleepers of Ephesus slept their long sleep in a cave. The
hills of Granada are still believed by the Moorish children to contain
the great Boabdil and his sleeping host, who will awake, when an
adventurous mortal invades their repose, to restore the glory of the
Moors in Spain.

Caves have been used in all ages by mankind for habitation, refuge and
burial. In the Old Testament we read that when Lot went up out of Zoar
he dwelt in a cave with his two daughters. The five kings of the
Canaanites took refuge from Joshua, and David from Saul, in the caves of
Palestine, just as the Aquitani fled from Caesar to those of Auvergne,
and the Arabs of Algeria to those of Dahra, where they were suffocated
by Marshal Pelissier in 1845. In Central Africa David Livingstone
discovered vast caves in which whole tribes found security with their
cattle and household stuff.

The cave of Machpelah may be quoted as an example of their use as
sepulchres, and the rock-hewn tombs of Palestine and of Egypt and the
Catacombs of Rome probably owe their existence to the ancient practice
of burial in natural hollows in the rock. We might therefore expect to
find in them most important evidence as to the ancient history of
mankind, which would reach long beyond written record; and since they
have always been used by wild beasts as lairs we might reasonably
believe also that their exploration would throw light upon the animals
which have in many cases disappeared from the countries which they
formerly inhabited. The labours of Buckland, Pengelly, Falconer, Lartet
and Christy, and Boyd Dawkins have added an entirely new chapter to the
history of man in Europe, as well as established the changes that have
taken place in the European fauna. The physical history of caves will be
taken first, and we shall then pass on to the discoveries relating to
man and the lower animals which have been made in them of late years.

_Physical History._--The most obvious agent in hollowing out caves is
the sea. The set of the currents, the force of the breakers, the
grinding of the shingle inevitably discover the weak places in the
cliff, and leave caves as one of the results of their work, modified in
each case by the local conditions of the rock. Those formed in this
manner