Practitioners of Tantric yoga are said to use certain diagrams, called yantras, as aids to meditation [1]. The most interesting of these, from a geometrical point of view, is the sriyantra (the great yantra). A version of diis, shown below, has been reproduced in various recent books and articles as an example of the mathematical achievements of early non-European cultures. In this article I want to make some observations about the geometric structure of the sriyantra, and to comment on some of the claims being made about it. I also hope, in passing, to be offering an example of the sort of geometric situation that can be explored with the powerful Cabri geometry program [2].

The series

is the simplest known series * which could be used to compute π, but it converges far too slowly to be of any practical use for this purpose. In this paper we prove an asymptotic formula for the remainder of the series (1) after a finite number of terms. The formula is

where

My recollections of W. J. Greenstreet date back half a century when we were both undergraduates at Cambridge, but we did not become personally acquainted till many years later. He had a slightly stooping figure and kind protective face which dissolved any feeling of awe produced by his great strength and height, penetrating eyes, and full-grown beard. He had two inseparable friends, E. F. J. Love and G. F. Stout. When in company together they drew the attention of every one who saw them. They looked more like three generations than contemporaries, Greenstreet being plainly the responsible head and Stout the cheerful but inscrutable infant, while Love appeared to be more normal and rather embarrassed by the strangeness of his companions.

In the last paragraph of an article entitled “Octahedra Inscribed in a Cube” by T. Bakos, Math. Gazette, Vol. XLIII pp. 17-20, (1959), the following statement is made: “About a cube (±b, ±b, ±b) one can circumscribe 3 regular octahedra (the edges of the octahedra through the vertices of the cube); their vertices are: