648 Notice of the Ajaib-al-Muhhlukat. [No. 152. 



like a shield or half a sphere. Most of the ancients are of opinion, that it 

 is a ball placed in the midst of the heavens, like the yolk of an egg 

 in the white. Some say the earth has nine sides : on each side men 

 stand with their feet to the earth, and their heads towards the sky. 

 Some say, it floats in the midst of the ocean. 



Pythagoras (<**«*£&**) thinks the earth revolves, and that the 

 apparent motion of the heavenly bodies, from East to West, is caused by 

 the motion of the earth from West to East. But this can never be ; for 

 if we liberate a pigeon in the air, it could never again return to us ; 

 since the earth must revolve more rapidly than a pigeon can fly.* 



The earth is divided into three parts; viz. 1st, the part above the 

 ocean ; 2nd, the part concealed by the ocean ; and 3rd, its centre or axis. 

 The surface is covered by vegetation and animals ; the interior is occu- 

 pied by ores, metals, &c. Only half of the heavens are visible at once : 

 but, if we move our position, on the earth's surface, we see parts of the 

 heavens which were not visible from the place which we first occupied, 

 at the rate of one degree of the heaven's surface for every 1 9 parasangs 

 we travel. f 



After a quotation from Abu Bihan's speculations on the earth's 

 diameter and circumference, the author alludes to the fact of the Caliph 

 Mamun causing the measurement of a degree to be made, (this was 

 done, A. D. 814, in the sandy plains of Mesopotamia, between Palmyra 

 and the Euphrates,) by which 56f miles were fixed as the equivalent 

 of a degree of the heaven's circumference. 



Batolimus, (Ptolemy), he goes on to state, divided the night and day 

 into 24 equal portions by the rising and setting of the sun. Having 

 ascertained that the sun traverses 15° of its path in an hour of time, 

 (24 X 15°= 360°,) he found, by observations of an eclipse of the sun at 

 two cities, (the distance between which was ascertained,) that a degree 

 of the sun's path was equivalent to every 75 Arabian miles of the earth's 

 surface, which being multiplied by 360 give 27,000 miles as the mea- 

 sure of the earth's circumference, (24,912 geographical miles are its 

 true circumference.) 



* This is the old objection of the Ptolemais to the Pythagorean or Copernican 

 system ; they forgot that the atmosphere, in which their pigeon flies, partakes of the 

 motion of the earth, and carries the pigeon along with it, at an equal rate with the 

 objects on the earth's surface. 



f Calculating the parasang at 3 miles, the terrestrial degree would be 57 miles. 



