The answer to this question turns upon the relevant provisions of the Act and they read: Section 10(2): Such profits or gains shall be computed after making the following allowances, namely: (vi) in respect of depreciation of such buildings, machinery, plant or furniture being the property of the assessee, a sum equivalent, where the assets are ships other than ships ordinarily plying on inland waters, to such percentage on the original cost thereof to the assessee as may in any case or class of cases be prescribed and in any other case, to such percentage on the written down value thereof as may in any case or class of cases be prescribed: Section 10(5) of the Act defines "written down value" thus: "written down value" means (a) in the case of assets acquired in the previous year, the actual cost to the assessee: (b) in the case of assets acquired before the previous year the actual cost to the assessee less all depreciation actually allowed to him under this Act or any Act repealed thereby, or under executive orders issued when the Indian Income tax Act, 1886 (II of 1886) was in force".