Here, then, we have Rhapta 33 leagues (100 miles = 1° 40′) beyond Menouthias. Captain Guillain (Prem. Partie, p. 115) would make the former correspond with the debouchure of the Oufidji river (Rufiji or Lufiji), in S. lat. 7° 50′. But the Periplus, unlike Ptolemy, alludes only to a port, not to a river mouth, nor does the coast-line here show any promontory. Others have proposed Point Puna (S. lat. 7° 2′ 42″), the south-western portal of the Zanzibar manche, near the modern trading port of Mbuamáji, which in former ages may have been more important. D’Anville, Vincent, and De Froberville boldly prefer Kilwa (in round numbers S. lat. 9°), which is distant 157 geographical miles from the southernmost point of Zanzibar, and I think they are right. It is safer in such matters to suspect an error of figures and of distances than of topography, especially where the geographical features are so well marked and cannot be found in other places. Computations of ancient courses and log-books can have little value except when they serve to confirm commonly topographical positions. Kilwa has ever been a central station on the Zanzibar coast, and the slaves brought from the interior are still remarkable for size. Moreover, as Dr Beke well observes (Sources of the Nile, p. 69), ‘In attempting to fix in the map of Africa the true position of Ptolemy’s lakes and sources of the Nile, we must discard all notions of their having been determined _absolutely_ by means of astronomical observations, special maps of particular localities, or otherwise, and regard them simply as derived from oral information, and as laid down _relatively_ to some well-known point or points on the coast.’[34] Zanzibar, the principal link in the chain of islets which extends from Makdishu (Magadoxo), in the Barr el Benadir or Haven-land, to Cape Corrientes, is a long narrow reef, with the major axis disposed from N. N. W. to S. S. E., and subtending a deep bight or bend in the coast, justly enough called the Barbaric Gulf. The length is 48·25 geographical miles from Ra’as Nunguwi, the northern (S. lat. 5° 42′ 8″ Raper), to Ra’as Kizimkaz, the southern, extremity (S. lat. 6° 27′ 7″ Raper). The breadth is 18 miles from the Fort in E. long. 39° 14′ 5″ Raper’s correction, to the continental coast in E. long. (G.) 39° 32′ 5″. French travellers assume a max. length of 83 kilomètres, and a max. breadth of 33. The capital (S. lat. 6° 9′ 6″) corresponds in parallel with the Pernambucan province to the west and with Java and central New Guinea to the east. The corrected longitude (laid down by Captain Smee in 1811 as E. lat. 39° 15′) gives a difference of Greenwich time 2^{h.} 36^{m.} and 56^{s.}. From Southampton round the Cape the run is usually laid down at 8500 miles, viâ Suez 6200. The Lesseps Canal has shortened the distance from Marseille by 2000 leagues, and thus has placed Zanzibar within 1600 leagues of the great port—in fact, about the distance of the Gaboon ex- colony.