In this investigation the so-called Friar’s Heel was used only as a convenient point for reference and verification in measurement, and no theory was formed as to its purpose. It is placed at some distance, as before mentioned, to the south of the axis of the avenue, so that at the date arrived at for the erection of the temple the Sun must have completely risen before it was vertically over the summit of the stone. It may be remarked, further, that more than 500 years must yet elapse before such a coincidence can take place at the beginning of sunrise. In an Appendix certain details of the observations are given. In the next chapter I propose to show that an independent archæological inquiry carried out, in a most complete and admirable way, just after Mr. Penrose and myself had obtained our conclusion, entirely corroborates the date at which we had arrived. [11] This chapter and the end of the previous one are mainly based on the paper communicated by Mr. Penrose and myself to the Royal Society (see _Proceedings_, _Royal Society_, vol. 69, p. 137 _et seq._). [12] _The Celtic Druids_. 4to. London. 1827. [13] _Stonehenge, &c._ 1880. [14] _Smithsonian Contributions to Knowledge_, vol. xviii. No. 232, table 9. Washington. 1873. For curve, see page 130. CHAPTER VIII ARCHÆOLOGICAL OBSERVATIONS AT STONEHENGE, 1901 Soon after Mr. Penrose and myself had made our astronomical survey of Stonehenge in 1901, some archæological results of the highest importance were obtained by Professor Gowland. The operations which secured them were designed and carried out in order to re-erect the leaning stone which threatened to fall, a piece of work recommended to Sir Edmund Antrobus by the Society of Antiquaries of London and other learned bodies, and conducted at his desire and expense. [Illustration: FIG. 16.--The arrangements for raising the stone, looking north-east.] They were necessarily on a large scale, for the great monolith, “the leaning stone,” is the largest in England, the Rudston monolith excepted. It stood behind the altar stone, over which it leant at an angle of 65 degrees, resting at one point against a small stone of syenite. Half-way up it had a fracture one-third across it; the weight of stone above this fracture was a dangerous strain on it, so that both powerful machinery and great care and precautions had to be used. Professor Gowland was charged by the Society of Antiquaries with the conduct of the excavations necessary in the work. The engineering operations were planned by Mr. Carruthers, and Mr. Detmar Blow was responsible for the local superintendence. Mr. Blow thus describes the arrangements (_Journal_ Institute of British Architects, 3rd series, ix., January, 1902):--