In books 2 through 7, he used degrees and put the meridian of 0 longitude at the most western land he knew, the "Blessed Islands", often identified as the Canary Islands, as suggested by the location of the six dots labelled the "FORTUNATA" islands near the left extreme of the blue sea of Ptolemy's map here reproduced.
I bog 2-7 brugte han grader og sætte meridianen 0 længdegrad ved det mest vestlige land, han kendte, de "Velsignede øer", ofte identificeret som De Kanariske Øer, som markeret af placeringen af ​​de seks prikker mærket "Fortunata"-øer nær den venstre ekstreme del af det blå hav på Ptolemæus' kort.