n made as to how the huge capstones of the
circle at Stonehenge were placed on the erect stones. Sir Henry Dryden
thought that when the upright stones were set on end, earth or small
stones were piled around them until a large inclined plane was formed,
on which "skids" or sliding-pieces were placed. Then the caps were
placed on rollers, and hauled up by gangs of men. Probably in some such
way these wonderful monuments were formed.

The last class of rude stone monuments is composed of dolmens, or
chambered tombs, so named from the Welsh word _dol_, a table, and _maen_
or _men_, a stone. They are in fact stone tables. Antiquaries of former
days, and the unlearned folk of to-day, call them "Druids' altars," and
say that sacrifices were offered upon them. The typical form is a
structure of four or more large upright stones, supporting a large flat
stone, as a roof. Sometimes they are covered with earth or stones,
sometimes entirely uncovered. Some antiquaries maintain that they were
always uncovered, as we see them now; others assert that they have been
stripped by the action of wind and rain, and snow, frost, and thaw,
until all the earth placed around them has been removed. Possibly
fashions changed then as now; and it may console some of us that there
was no uniformity of ritual even in prehistoric Britain. Dolmens contain
no bronze or iron implements, or carvings of the same, and evidently
belong to the time of the Neolithic folk.

Among prehistoric remains none are more striking than the great camps
and earthworks, which hold commanding positions on our hills and downs,
and have survived during the countless years which have elapsed since
their construction. Caesar's camps abound throughout England; it is
needless to say that they had nothing to do with Caesar, but were made
long years before the Conqueror ever set foot on British land. These
early camps are usually circular in shape, or follow the natural curve
of the hill on which they stand. Roman camps are nearly always square
or rectangular. They consist of a high vallum, or rampart of earth,
surrounded by a deep ditch, and on the _counterscarp_, or outside edge
of the ditch, there is often another bank or rampart. The entrance to
these strongholds was often ingeniously contrived, in order that an
enemy endeavouring to attack the fortress might be effectually resisted.

Chun Castle, in Cornwall, is an interesting specimen of ancient Celtic
fortress. It consist