1875.] G. Thibaut— On the S'ulvasutras. 263 



Tbe nave is to be circumscribed at its borders with a circle, i. e. the 

 square forming the nave is to be turned into a circle. This was of course 

 executed according to the general rule which has been discussed above. 



After having likewise turned into circles the squares, marking the outer 

 and inner edge of the felloe — 



One divides the area lying between felloe and nave into thirty-two parts, 

 and takes out the second, fourth, sixth, &c, parts. 



That means : the second, &c, parts are excluded from the agnikshetra 

 and not to be covered with bricks. 



^wn=rPT ^5^T *rat% I 



In this manner the added part (i. e., the sixty-four bricks by which 

 the square of 289 bricks exceeded the legitimate area of the saptavidha agni) 

 is removed again. 



By following all the preceding directions we get indeed a wheel, the 

 area of which (with exclusion of the interstices between the spokes) is equal 

 to that of the saptavidha agni ; of course, we have to make the necessary 

 allowance for the inevitable error introduced by the square having to be 

 turned into a circle. It remains to retrace the steps by which Baudhayana 

 succeeded in rendering the area of the sararathachakra pretty well equal to 

 that of the chaturasra s'yena. 



A look at the diagram of the sararathachakraehit shows at once that 

 one preliminary question must first be settled, the question what the 

 relative size of the wheel's different parts was to be. As far as we can see, 

 there was no fixed rule regarding this matter, and wheels of various shapes 

 might therefore have been adopted. Baudhayana does not state at the 

 outset what the shape of his wheel will be, but from the result of his rules 

 we may conclude his intention. The entire square — or the entire circle into 

 which the square is turned — comprises 289 bricks, or simpler 289 parts, of 

 which 145 form the felloe, the remaining 144 the spokes, interstices, and the 

 nave. It appears therefore probable that Baudhayana' s intention was to 

 allot to the felloe an area equal to that of spokes, &c, together. The reason 

 why the two parts were not made exactly equal will appear from the fol- 

 lowing. 



The task was, in the first place, to draw two squares — representing the 

 outer and the inner edge of the felloe — the area of one of which was the 

 double of the area of the other. For this purpose Baudhayana made use 

 of his " savis'esha," i. e., of the rule teaching that the square of 16 -fj is 

 almost equal to double the square of 12 ; only he substituted here, in order 

 to facilitate the operation, 17 to 16 -||. Accordingly, he began by drawing 

 a square the area of which amounted to seven and a half square purushas, 



