The position given by Ptolemy agrees fairly well with Al-Sufi's description, although the place is slightly erroneous, as is also the case with Fomalhaut and β Centauri. It is impossible to suppose that either Ptolemy or Al-Sufi could have seen α Eridani, as it is too far south to be visible from their stations, and, owing to the precession of the equinoxes, the star was still further south in ancient times. Al-Sufi says distinctly that the distance between Ptolemy's 33rd star (which is undoubtedly _h_ Eridani, or Proctor's υ') and the 34th star was "4 cubits," or 9° 20'. The actual distance is about 9° 11', so that Al-Sufi's estimate was practically correct. Halley, in his _Catalogus Stellarium Australium_, identifies Ptolemy's star with θ Eridani, and Baily agreed with him.[430] Ulugh Beigh also identifies the "Last in the River" with θ Eridani. The Arabic observer Mohammed Ali Achsasi, who observed in the seventeenth century, called θ Eridani _Achr al-nahr_, and rated it first magnitude.[431] To argue, as Bode and Flammarion have done, that Ptolemy and Al-Sufi may have heard of α Eridani from travellers in the southern hemisphere, is to beg the whole question at issue. This is especially true with reference to Al-Sufi, who says, in the preface to his work, that he has described the stars "as seen with my own eyes." α Eridani is over 11 "cubits" from _h_ Eridani instead of "4 cubits" as Al-Sufi says. This shows conclusively that the star seen by Al-Sufi was certainly _not_ α Eridani. The interest of the identification is that Al-Sufi rated θ Eridani of the _first_ magnitude, whereas it is now only 3rd magnitude! It was measured 3·06 at Harvard and estimated 3·4 by Stanley Williams, so that it has evidently diminished greatly in brightness since Al-Sufi's time. There is an interesting paper on this subject by Dr. Anderson (the discoverer of Nova Aurigæ and Nova Persei) in _Knowledge_ for July, 1893, in which he states that the "Last in the River," according to the statements of Hipparchus and Ptolemy, _did_ rise above their horizon at a certain time of the year, which α Eridani could not possibly have done. This seems sufficient to settle the question in favour of θ Eridani. Dr. Anderson says, "It is much to be regretted that Professor Schjellerup, the able and industrious translator of Sufi, has allowed this to escape his notice, and helped in the preface and note to his work to propagate the delusion that α Eridani is Ptolemy's 'Last in the River'"; and in this opinion I fully concur. Al-Sufi's clear account places it beyond a doubt that the star known to Hipparchus, Ptolemy, Al-Sufi, and Ulugh Beigh as the "Last in the River" was θ Eridani. θ must have diminished greatly in brightness since Al-Sufi's time, for in ranking it as 1st magnitude he placed it in a very select list. He only rated thirteen stars in the whole heavens as being of the 1st magnitude. These are: Arcturus, Vega, Capella,