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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 Mipar 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.
In another section, dealing with cloth (IV.1.18-37), Pheru mentions different kinds of silk, woollen and cotton materials, the rate of shrinkage or loss in washing, cutting and sewing, and the area of cloth needed to make various types of tents. There is a last section (IV.iii.1-17) listing the average yields of grains, pulses, etc. per bighā, the average yield of molasses and brown sugar per maund of sugarcane, the amount of clarified butter that can be obtained from cow's and buffalo's milk and so on. Mention must also be made of Pheru's rule for converting Vikrama dates into Hijri dates and vice versa (IV.1.17) which is probably the first such rule to be formulated in India. It must be emphasised that all this is not germane to arithmetic as such, but Pheru is adapting arithmetic here to suit the needs of a variety of professions.
2.5 The Dhātut patti, also not dated, deals with a heterogeneous mixture of topics, namely origin of metals, extraction of metals and perfumery articles. In the shape it has come down, the text does not seem to be complete or even continuous. Perhaps here are separate extracts from the lost Bhūgarbhaprakāśa said to have been written by Pheru. Even so, the present text offers valuable material. The section on the perfumery articles describes the properties, varieties, provenance and prices of camphor, aloe-wood, sandal-wood, musk, saffron etc. But more important is the section which discusses the techniques of extracting or preparing brass, copper, lead, tin, bronze, mercury, vermillion, red lead etc. This and the first part of the Dravyapariksa (to be discussed below) show Pheru's familiarity with metal technology, and are unique contributions to the history of metallurgy in medieval India.
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