There is also another circle of smaller upright stones, respecting which the only point requiring notice now is that none of them would have interrupted the line of the axis of the avenue. The circular temple was also surrounded by the earthen bank, shown in Fig. 15, of about 300 feet in diameter, interrupted towards the north-east by receiving into itself the banks forming the avenue before mentioned, which is about 50 feet across. Within this avenue, no doubt an old _via sacra_, and looking north-east from the centre of the temple, at about 250 feet distance and considerably to the right hand of the axis, stands an isolated stone, which from a mediæval legend has been named the Friar’s Heel. [Illustration: FIG. 15.--General plan; the outer circle, naos and avenue of Stonehenge. _F.H._ = Friar’s Heel.] The axis passes very nearly centrally through an intercolumniation (so to call it) between two uprights of the external circle and between the uprights of the westernmost trilithon as it originally stood. Of this trilithon the southernmost upright with the lintel stone fell in 1620, but the companion survived as the leaning stone which formed a conspicuous and picturesque object for many years, but happily now restored to its original more dignified and safer condition of vertically. The inclination of this stone, however, took place in the direction of the axis of the avenue, and as the distance between it and its original companion is known both by the analogy of the two perfect trilithons and by the measure of the mortice holes on the lintel they formerly supported, we obtain by bisection the distance, 11 inches, from its edge, of a point in the continuation of the central axis of the avenue and temple. The banks which form the avenue have suffered much degradation. It appears from Sir Richard Colt Hoare’s account that at the beginning of the last century they were distinguishable for a much greater distance than at present, but they are still discernible, especially on the northern side, for more than 1300 feet from the centre of the temple, and particularly the line of the bottom of the ditch from which the earth was taken to form the bank, and which runs parallel to it. CHAPTER VII ASTRONOMICAL OBSERVATIONS AT STONEHENGE IN 1901[11] An investigation was undertaken by Mr. Penrose and myself in the spring of 1901, as a sequel to analogous work in Egypt and Greece, with a view to determine whether the orientation theory could throw any light upon the date of the foundation of Stonehenge, concerning which authorities vary in their estimates by some thousands of years. Ours was not the first attempt to obtain the date of Stonehenge by means of astronomical considerations. In Mr. Godfrey Higgins’ work[12] he refers to a method of attack connected with precession. This furnished him with the date 4000 B.C.