Instruments of the Antienls. 233 



in uncertainty and doubts which we cannot resolve. We 

 are often obliged to content ourselves with probabilities; and 

 at best we can only arrive at a degree of certainty propor- 

 tional to the number, quality, and circumstances of monu- 

 ments and historical testimonies. 



51. " The testimonies of the existence of Ptolemy's mir- 

 ror on the Pharos, are not commonly thought to have the 

 authenticity necessary for the solid establishment of a his- 

 torical fact. Two reasons, which at first sight appear plau- 

 sible, may be alleged for the rejection of those testimonies. 



52. " The first reason is, that some authors attribute this 

 mirror to Ptolemy, and others to Alexander the 'Great. 

 John Baptista Porta, father Kircher, and father Gaspard 

 Schottus, are among those who place the construction of 

 this mirror in the time of Ptolemy. M. de la Martlniere, 

 in his Geographical Dictionary, cites Martin Crushes, who 

 in his Turco-Grcecia says, on the authority of the Arabians, 

 that M Alexander the Great caused to be placed on the top 

 of the Pharos tower, a mirror made with such art, that in 

 it might be seen 500 parasangas, or above 100 leagues of}', 

 hostile fleets coming against Alexandria or against Egvpt, 

 and that after the death of Alexander, this mirror was broken 

 by a Greek named Sodor, who watched his opportunity 

 when the soldiers in the fort were asleep: 



53. " But this difference of opinion respecting the origin 

 of the mirror cannot affect the truth of the fact. For it 

 often happens in history, that different authors attribute the 

 same fact to different men, without our regarding the fact 

 itself as fabulous. Of this we have an example in the erec- 

 tion of this very tower, the Pharos, which is ascribed by 

 some to Alexander, and by others to Ptolemy. It would 

 seem that they who have spoken of the mirror, have thought 

 that it was constructed by the very person who built so won- 

 derful an edifice. 



54. " The second, and the strongest, reason against the 

 existence of this mirror, is the impossible circumstances 

 and properties which historians ascribe to it. Paul Aresa, 

 bishop of Tortona, in his Impresa Sacra, Impr. 54. n. 1 

 and 2, cited by Scarabelli in his Museo SeHaliano, says : 

 i( He knew that Ptolemy saw, 600 miles off, fleets coming 

 to the port of Alexandria, not by strength of sight, bat by 

 the virtue of a crystal or glass." But he adds, " that he 

 suspected the truth of this fact, on account of the rotundity 

 of the earth, which rendered it impossible." 



55. " But I maintain, that this circumstance of seeing 

 600,000 paces, or 500 parasangas off, totally impossible as 



H3 it 



