( 1 ) THE petitioner is the karta of a joint Hindu mitakshara family consisting of his sons and other descendants. The said joint family carries on business under the trade name of "goenka Coal Company" (hereinafter referred to as the said firm ). The said firm owns a colliery known as "goenka Kajora Colliery" situated at P. O. Ukhra; District. Burdwan. The said firm is a registered dealer under the Bengal Finance (Sales Tax) Act, 1941 (hereinafter referred to as the said Act ). The said firm is also a registered dealer under the Central Sales Tax Act, 1956. It is stated that for the raising of coal, the said firm had installed several machineries and equipments and used such machineries and equipments and other stores for raising coal from the said colliery. The machineries and equipments so installed at the said colliery and the stores are occasionally sold or disposed of when they become old and unserviceable. It is stated that the sales of such old and discarded machineries, equipments and stores do not form any part of the business activities of the said firm, which consisted mainly of raising of coal from the said colliery and selling the same. It is furth