HISTORY OF BOTANY. 29 



ference of the earth, making it ahout 24,000 of our miles; 

 ascertained the length of a degree right within one-third of 

 a mile ; translated the chief Greek philosophers into Arabic ; 

 produced numerous writings on mechanics, hydrostatics and 

 optics ; invented apparatus for distilling, fusing, &c. ; pro- 

 duced great improvements in geometry; invented algebra; 

 and especially improved chemistry, preferring experiment 

 to speculation. They first established medical colleges, 

 introduced the Indian numbers, made catalogues and maps 

 of the stars, fixed the length of the year, and verified the 

 precession of the equinoxes. They first used the pendulum 

 as a time measurer, discovered sulphuric acid, nitric acid, 

 and alcohol, first published pharmacopoiias, and included in 

 them minerals. In agriculture they improved irrigation, 

 the method of employing manures, and the breeding of 

 cattle. In manufactures they made Cordova and Morocco 

 leather and paper, and Toledo blades, and improved mining. 

 They taught Europe chess, and gave it its taste for romances 

 and music of a high order. 



With regard to Botany there were, as we have seen, many 

 writers, and we also find several important additions to our 

 knowledge ; still, taking into account the information they 

 obtained from Galen and others, and the long period of 

 time, the progress made was not so great as might have 

 been expected, especially w^hen compared with their great 

 achievements in other Sciences. 



