106 



CHAP. XVIII. 



Of the fraction of Light, and Astronomical Re- 

 fraction, and of Perspective. 



1^ 

 HE Arabians applied themselves with much as- 

 siduity to the vStudy of the sciences, and the situation 

 of their climate Jed them to prefer astronomy, which 

 they cultivated very *arly. There are a considerable 

 quantity of their writings in our large repositories for 

 hooks, which ha?e never yet come under our notice, 

 having s tiH remained in manuscript in their original 

 language: so great has been our neglect of them for 

 some ages. Yet those who have been at the pains cu- 

 riously to ransack those manuscripts, have been well 

 rewarded for their trouble, by the acquisition they 

 have thence made of many new and original ideas, and 

 the information they have received of various inven- 

 tions and discoveries useful, and entertaining. A learn- 

 ed gentleman at Oxford, who carefully examined the 

 Arabian manuscripts in the famous library of that uni- 

 versity, givefr his sanction to this in a manner that 

 should engage others to imitate his example ift such re- 

 searches. Among other motives naturally teiu iUg to 

 produce this etiect, he says, 4i The advantages recom- 

 mending the study of astronomy to the people of the 

 cast were many. The serenity of their weather, the 



