word has been said as to the arrangement of mortice and
tenon, by which the Trilithons are keyed together. This has been done
purposely, in order that the constructional questions relating to
Stonehenge should, as far as possible, be dealt with together, and in
due order. In the outer circle of Trilithons each upright had two
tenons worked on its apex, to bear the two lintels or horizontal
stones which rested upon it. Corresponding mortices were sunk in
those stones to admit the tenons. In the case of the Trilithons of the
Inner Horseshoe, only one tenon on each upright was necessary.
Further, the ends of the lintels of the outer circle were shaped so as
to dovetail into one another, and form what is known as a "toggle"
joint. This can easily be seen to-day, in the group of three
Trilithons which lie between the Altar Stone and the Hele Stone. This
careful arrangement, of mortice, tenon, and toggle, has doubtless very
much to do with the comparative stability of Stonehenge at the present
day. Had these simple but effective measures not been taken, it would
not be exceeding the bounds of possibility to say that to-day the ruin
would have presented a mass of fallen stones, and the task of their
reconstruction would be well-nigh impossible.

[Illustration]

Evidently the early mason found the cutting of these tenons by no
means an easy task, for, with two exceptions, the workmanship is not
remarkable. Luckily for the observer to-day the tenon on the remaining
upright of the Great Trilithon is very strongly marked, and stands out
boldly on its apex, thus affording a clue to those existing on other
stones. The mortice holes were easier to accomplish. A small
depression may have been made first of all, and then a round stone
inserted with sand and water. In this way a smooth hollow could soon
be worn. This principle is and has been applied by stone-using peoples
in all quarters of the globe. The rough dovetailing of the lintels of
the outer circle would present no difficulty to users of the tools
already mentioned.

To-day the surfaces of the Sarsens bear undoubted signs of weather,
but in the Stonehenge of yesterday the Sarsens were beautifully
finished with rough tooling all over their surface. This final finish
was achieved by the Quartzite Hammers (Class IV.). A very beautiful
piece of this work was discovered by Mr. Gowland in 1901. In the
process of raising the upright of the Great Trilithon, a thin slab of
that p