These are based on the Ṭáṇk and the Surkh. A Ṭáṇk is equal to twenty-four Surkh, and the ordinary Misḳál is two Surkh more. The Surkh is divided into twenty parts, each part being termed a biswah. Formerly two and a half biswah were reckoned to one rice-grain, but the grains of that time were larger. His Majesty's foresight and sagacity have adjusted the proportion of two biswah to the grain. Each Surkh was equal to ten rice-grains. His Majesty in his wisdom directed that the grains should be made of the cat's eye stone and thus obviated the defect of currency. The standard weights kept ready for use are the following: the biswah, the rice-grain, ¼ and ½ of Surkh, 2 Surkh, 3 Surkh, 6 Surkh (which is ¼ of a Ṭáṇk), ½, 1, 2, 5, 10, 20, and 50 Ṭáṇk. Any other gradations may be compounded of these weights, and for the imperial service, weights of cat's eye up to 140 Ṭáṇks have been made of such brilliancy that they cannot be distinguished from gems.