But, assuming. that the question is still open because it was never directly raiijed in this Court and specifically decided, we a!'e of opinion that. the income-tax rules shoulcl be appliecl ip working out depreciation under the Fn 11 Bench formula in preference to the provisiou~ of the Seventh Schedule to tho Electricity (Supply) Act. It was pointed out in T·innvellyTuticori:n Electriq 8upply Go.'8 mse (1 ) that 1..he provisions in tl,le Electricity (Supply) Act contained in s. 57 and the Sixth ancf Seventh Schedules to the Act were for a special purpose, namely, to work :out t.he charges to be recovered from consum<>rs for the supply of electricity. It was also observed that the provisions of the Electricity (SnJ)ply) Act and its Schedules were meant. for operation .in the field covered by the Act and t.hat the principles of industrial adjudication were wholly different and hacl to be worked out in their own way in the industrial field. It seems to us therefore that in working ou't available sur1ilus according to the Full Bench' formula, the same prinoiple with respect to depreciation should be applied in tbe case of electricitx companies as in the case of all other industrial concerns. As the ,Appellate Tribunal pointed out, the result in the long run would be the same, though there might be difference in some vears. Besides, in the foi·muln. when it was evolved in 1950 (see The ivlill-Owners' .Assoc·iation· 'v.-The Rashtriya ~f!ill'Jfazdoor f::ia,n.yh Bombay.('), the' depreciation intended to be allowed was as provided in th{: rules under the Income-tax Act. The Appelhte Tribunal pointed this out. in t·hP [·. P. Ehc:tric S·tipply Oompan's case (') and said the Full Bench formula allowed depreciation according to incometa.x rates. It seems tu us therefore that in the field of iudustriti.l relations in connection with which the Full Bench formnla was 0voh·ed