The clause as amended by section 8 of the Indian Income tax (Amendment) Act 25 of ' 1953 with effect from April 1, 1952, reads as follows : "In respect of depreciation of buildings newly erected, or of machinery or plant being new which has been installed, after the 31st day of March, 1948, a further sum (which shall be deductible in determining the written down value) equal to the amount admissible under clause (vi) (exclusive of the extra allowance for double or multiple shift working of the machinery or plant and the initial depreciation allowance admissible under that clause for the first year of erection of the building or the installation of the machinery or plant) in not more than five successive assessments for the financial years next following the previous year in which such buildings are erected and such machinery and plant installed and falling within the period commencing on the 1st day of April, 1 949, and ending on the 31st day of March, 1959.