  In Book 8 of his Geographike Hyphegesis Ptolemy gives coordinates for ca. 360
so-called noteworthy cities. These coordinates are the time difference to
Alexandria, the length of the longest day, and partly the ecliptic distance
from the summer solstice. The supposable original conversions between the
coordinates in Book 8 and the geographical coordinates in the location
catalogue of Books 2-7 including the underlying parameters and tabulations are
here reconstructed. The results document the differences between the $\Omega$-
and $\Xi$-recension. The known difference in the longitude of Alexandria
underlying the conversion of the longitudes is examined more closely. For the
ecliptic distances from the summer solstice of the $\Omega$-recension it is
revealed that they were originally computed by means of a so far undiscovered
approximate, linear conversion. Further it is shown that the lengths of the
longest day could be based on a linear interpolation of the data in the
Mathematike Syntaxis 2.6.
