(f) A ring of hewn Sarsen stones with "imposts" or lintels mortised to them. The lintels are fitted together with toggle joints. Sixteen out of the original thirty uprights of these "Trilithons" are now standing.
The diameter of this circle is about 108 feet, or that of the dome of St. Paul's. ([See page 12.])
(g) A ring of less perfectly hewn "Foreign Stones" (i.e. stones not to be found in Wiltshire at the present day).
These numbered between thirty and forty. Only seven are standing to-day, nine are overthrown. ([See page 20.])
(h) Five great Trilithons, arranged in a horseshoe, with the opening to the north-east. These Trilithons rise gradually in height towards the south-west. The largest group of stones fell A.D. 1620. Those next to the great Trilithon on the north-west, fell on January 3rd, 1797.
To-day only two of the Inner Trilithons are standing. One upright of the great Trilithon (raised and made secure in 1901) is erect. ([See page 17.])
(i) A horseshoe of less perfectly hewn Foreign Stones. Originally there were fifteen or more of these monoliths averaging eight feet high. ([See page 20.])
(j) A simple recumbent slab of micaceous sandstone called the "Altar Stone." ([See page 14.])
III. Where the Stones came from
(a) The Sarsen Stones are the remains of a cap of Tertiary Sandstone which once covered the plain. ([See page 17.])