CHAPTER XV.
The same relation is derived from the old theory,
which Yakiib Ibn Tarik mentions in his book, Com-
positio Sphccrarum, on the authority of his Hindu
informant, viz. that the circumference of the zodiac
is 1,256,640,000 yojana, and that its diameter is
400,000,000 yojana.
These numbers presuppose the relation between cir¬
cumference and diameter to be as i : 3 tV^-fow^rnro-
These two numbers may be reduced by the common
divisor of 360,000. Thereby we get 177 as numerator
and 1250 as denominator. And this is the fraction
(iWo") which Pulisa has adopted.