774 Description of a Persian Astrolabe, [No. 118. 



Mecca, Medina, and Ispahan, and a few others, have their latitudes and 

 longitudes pretty correctly assigned ; those of inferior note seem to 

 have had them very carelessly observed, or perhaps merely guessed. 

 I must at the same time confess my belief that, generally speaking, 

 European mathematicians have not done their Arabian predecessors 

 full justice, in respect at least to their longitudes ; but that having 

 assigned to them a first meridian from which they did not compute, 

 they have unintentionally attributed to them errors that sprung from 

 themselves. 



The first meridian among the Greeks passed through the " Fortunate 

 Islands," a meridian which Ptolemy adopted, and from which he made 

 his calculations. These islands have been pretty generally believed to 

 be the Canary Isles, probably from the circumstance of their lying 

 at the Western extremity of Europe. I am rather inclined to think, 

 however, that the place from which Grecian geometers, (and conse- 

 quently their imitators, the Arabs,) commenced their longitude, was an 

 imaginary one, and that therefore, like the Lanca of the Hindoos, 

 its position was never satisfactorily ascertained. 



The Fortunate Isles probably owed their origin primarily to the* 

 fabled Hesperides, and, secondarily, to that copious fertility of inven- 

 tion that sprung into existence about the time of Alexander, and which 

 may be traced downwards to that of Columbus himself: an invention 

 which filled up the blanks of unexplored regions with mysterious and 

 delightful lands, untrodden by the foot of ambition, where the golden 

 age still lingered in its bright perfection. Diodorus informs us, that 

 the Tyrant Cassander sent one Gohemerus on an exploratory voyage, 

 and that he discovered the island of Panchaia, astonishing for its 

 wealth, and the innocence of its inhabitants : where the most perfect 

 happiness, peace, justice, and voluntary obedience to the laws, had 

 flourished for thousands of years; this was indeed a fortunate island, 

 and probably the father of our family. Pliny the second informs us, 

 that it was in his day believed by some, that the Hesperid^s still existed 

 somewhere in that direction, but that there was much doubt upon 

 the subject. He also states indeed, giving his authority, that the 

 Fortunate Islands lie under the first meridian. " Juba de Fortunatis ita 

 inquisivit ; sub meridiem positas esse prope occasum a Purpurariis 

 DCCXXV.M. passuum sic ut ccl supra occasum navigetur: deinde 



