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JAIN JOURNAL
(iii) But where there is no traditional literature to lean on, he writes from his practical knowledge, and is most original and precise (e.g. on the gems imported from Persia). The Dhātutpatti (see 2.5) and more particularly the Dravyaparikşā (see 2.6) belong to this category of original works.
2.4 The Ganitasāra on arithmetic is not dated but must have been written before 1318. Compared to the previous text, this one is more innovative, not so much in the theoretical portions but in the application of arithmetical rules to a wide range of areas. It is a commonplace to say that arithmetic is one of the most practical of sciences, its rules being employed by traders, masons, carpenters, tax-collectors and the like for the calculations connected with their professions. The units of measurement and the examples to illustrate arithmetical rules given by Pheru throw a flood of light on the economic and social conditions of this period. Here a few examples will suffice.
In the section on solid geometry, Pheru gives the rules for the volumes of domes (gonamța), square and circular towers with spiral stairways in the middle (pāyaseva), towers with fluted columns (munāraya), niches (tāka), staircases (sopāna), bridges (pulabamdha) and so on (III. 74-86). It should be noted that some of these are new architectural features being introduced by the Muslim rulers in India in this period. The purpose of such rules is to enable the chief mason to calculate the number of bricks or stones needed for these constructions. To do this calculation more exactly, Pheru informs us, one should first calculate the total volume of the wall-space subtract from this the volume of the space occupied by the doors and windows and then reduce the remainder by threetwentieths, the latter being the volume of the morter (III. 70-71). The result when divided by the volume of a single brick yields the number of bricks.
Historically more significant is the following statement : “The munāraya is like a circular tower with a spiral stairway in the middle, as far as the inside is concerned. But the difference is this : the wall contains half triangles and half circles” (III.80). The meaning of the cryptic last sentence is that in a horizontal cross-section of the munāraya, the outer circumference consists of alternate triangles and semicircles. It should be remembered that about a hundred years before this time, Qutbuddin Aibak built the Qutb Minar in Delhi and that Alauddin himself started constructing another tower twice as high. Now, the lower story of the Qutb Minar consists of alternately angular and circular columns, and it is clear that Pheru is referring here to such a tower with fluted columns.
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