rind, while he was coming home, he noticed an image of the- ain projected through a narrow aperture in a fence of palma leaves close to his house. This phenomenon well known to every tyro in physical science made him reflect, and he thought that he had got a solution of his problem. Could he but get the sun's real diameter! The similar triangles on the two sides of the aperture, with their bases formed by the sun and his image, would enable him to find the distance. He bastened bome, but before he looked into any work for the sun's true diameter, he saw his error. For, was he not assuming the thing he wanted to find out ? And his exultation was followed by despair. At this stage the problem rested for several years, till he became acquainted with rules for calculating eclipses. He found that the parallax of the sun assumed in the Siddhantas was too large to make predictions of eclipses correct. The annular and total eclipses, together with those in which the -moon just grazes the shadow, were his landmarks in the determination of the problem. He was for some time in a sen of doubt. Perhaps the Siddhántas were wrong in the matter of parallax, as in many other matters. Perhaps his observations 'were not made with that degree of accuracy which was demanded by such problenis. These questions were never out of his mind for a single day through a long year. An accident favoured him. He was reading the Atharvan Upanishad, and was surprised to find that the sun's diameter was not 6500 yojanas as given in the Súrya-Siddhánta, but 72000 yojanas ! This gave him a fresh Digitbed by Google
