VEERASWAMI, J. : This petition is for a rule of mandamus directing the respondent, Union of India, represented by the Ministry of Finance, to issue a recognition that die Central Government is satisfied that the petitioners are engaged in the manufacture of one or more of the articles specified in Part A of the Fifth Schedule to the Income-tax Act, 1961. The petitioners are a public limited company incorporated in 1954, and are said to be engaged during the relevant time in the manufacture of grinding wheels and abrasives, being the industrial machinery specified in sub-clause (iii) of clause C of Part A of the Fifth Schedule to the Income-tax Act. The petitioners, as they aver, are assessed to income-tax by the First Income-tax Officer City Circle for 1960-61 and 1961-62, and in the course of these assessments they claimed that their profits in the manufacture of grinding wheels were exempt from income-tax under S. 15-C of the Indian Income-tax Act 1922. This contention, according to the petitioners, was accepted, and exemption granted under that provision. After the coming into force of the new Act with effect from 1-4-1962, which would have effect on the petitioners' as