Footnote 65: Wanderungen durch das Nilthal, von G. Parthey, Berlin 1840. 378. Footnote 66: Travels, pp. 9 and 11. Footnote 67: Eastern Life, i. 10½. Footnote 68: _Ib._, 144. Although we have no accurate measurements of the velocity of the Nile in Nubia, we may arrive at an approximate estimate of it by comparing its fall with that of a river well known to us. I have stated the fall of the Nile in different parts of its course to be 5·30, 9·00, 12·00, and 13·12 inches in a mile. The fall of the Thames from Wallingford to Teddington Lock, where the influence of the tide ends, is as follows:-- +------------------------------------------------------------------+ | | | | Fall in | | |Length of | Fall. | inches | | | course. | |per mile.| +-----------------------------------+----------+---------+---------+ | |Miles. F. |Feet. in.| | |From Wallingford to Reading Bridge,| 18·0 | 24·1 | 15·72 | |From Reading to Henley Bridge, | 9·0 | 19·3 | 25·68 | |From Henley to Marlow Bridge, | 9·0 | 12·2 | 16·20 | |From Marlow to Maidenhead Bridge, | 8·0 | 15·1 | 22·32 | |From Maidenhead to Windsor Bridge, | 7·0 | 13·6 | 23·16 | |From Windsor to Staines Bridge, | 8·0 | 15·8 | 23·52 | |From Staines to Chertsey Bridge, | 4·6 | 6·6 | 17·28 | |From Chertsey to Teddington Lock, | 13·6 | 19·8 | 17·40 | | +----------+---------+---------+ | | 77·4 | 125·11 | | +------------------------------------------------------------------+ "In general, the velocity may be estimated at from half-a-mile to two miles and three-quarters per hour; but the mean velocity may be reckoned at two miles per hour. In the year 1794, the late Mr Rennie found the velocity of the Thames at Windsor two miles and a half per hour."[69] Footnote 69: Rennie, Report on Hydraulics, in the Fourth Report of the British Association for the Advancement of Science, 1834, p. 487.