PROGRESS AMONG THE ARABS. 33 



(59 604), and will be again in Mexico and Peru, will 

 sweep away wealth, industry, commerce, culture, schools, 

 palaces all that recalled the hated Saracen, and replace all 

 this by the DEADLY INQUISITION. But the hated Saracen 

 will have left his mark. For, happily, Europe, that part of 

 it at least which was not wholly under the baneful sway of 

 the monks and the popes, Europe we say has inherited 

 much from him, and it has enlarged that heritage for the 

 benefit of the whole of mankind. 



We may now pro:eed to give a summary of the Arabian 

 achievements in the field of science, beginning it with the 

 mathematical and astronomical branches. 



IXth c. Ben Musa, a famous teacher, and the earliest 

 author on ALGEBRA, substituted sines for chords thus 

 furthering the science of trigonometry and found the com- 

 mon method of solving quadratic equations. He brought 

 into use the INDIAN NUMERALS, i, 2, 3, 4, 5, etc. Algebra 

 is known to have originated in India. It had been used as 

 early as the Vth century A.D. by the Greek Diophantus of 

 Alexandria ; but the Arabs perfected it and brought it to us. 



805 885. Albumazar drew up astronomical TABLES 

 calculated from his own observations of the stars. 



813834. Al Mamun (in 830) directed two observations 

 on the obliquity of the ecliptic (to measure it afresh) to be 

 made by the astronomers and mathematicians around him 

 (the result being 23 35' 52") ; he also ordered the accurate 

 .measurement of the magnitude of the earth's circumference 

 by the measuring of a DEGREE (found to be 56! miles) ; 

 caused the works of Aristotle, Euclid, Ptolemy, and Hippo- 

 crates to be translated into Arabic. 



823. Alfergani excelled in astronomical CALCULATIONS 

 based upon his direct observations. His works on astronomy 

 were translated, and studied in Europe for a long period. 



850 900. Geber Al Batani (Albategnius) discovered 

 the motion of the sun's apogee showing Ptolemy's error 

 (of 17) ; calculated the length of the year more accurately 

 than Ptolemy, making it 365 days 5 hours 46 min. 24 sec. 

 within two minutes of the exact time. He corrected other 

 errors in the observations of Ptolemy ; established tables of 



