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.) (_b_) The Foreign Stones are still a matter of debate. They have assuredly been brought from a distance. This is unusual; megalithic structures are usually built of materials found close at hand. (See page 20.) [Illustration: Stonehenge. Looking towards the South East.] IV. HOW THE MONUMENT WAS ERECTED The large monoliths of Sarsen Stone were first of all roughly shaped as they lay _in situ_ on the Plain and then transported to the chosen site. The Foreign Stones were also dressed on the spot before erection. The entire work was performed with stone tools of the roughest description, weighing from half a pound to over sixty pounds. (See p. 40.) The only trace of metal discovered in 1901, was a small stain of bronze on one stone, caused by contact with the stone of some very small bronze object, possibly an ornament. (See page 53.) The large Trilithons were erected from the centre of the site. The Foreign Stones were placed in position afterwards. (See pages 45-49.) V. STONEHENGE AND THE SUMMER SOLSTICE It is a notable fact that the sun rises immediately over the summit of the "Hele Stone," in a line with the axis of Stonehenge on the Summer Solstice. Sir Norman Lockyer and Mr. Penrose, working on astronomical grounds, fix the date of the circle at 1680 B.C., with a possible error of 200 years on either side. Much has been said as regards Sun Worship at Stonehenge. The exact use to which the circle was put is at present a matter of conjecture. (See page 57.) VI. STONE CIRCLES GENERALLY, AND STONEHENGE 1. Stonehenge is probably the latest, and is certainly the most elaborate, stone circle in England. 2. It is the only one in which the stones are squared, dressed, and provided with lintels or imposts. 3. It is the only circle which contains a "horseshoe" arrangement of stones. 4. Most of the stone circles in the South of England face towards the north-east. Stonehenge is one of these.