is in itself an effective and meaningful "supervision" as envisaged under Section 2(9) of the , 19,;8 (,for short the Act)? The said provision, as it stood at the relevant time, is set out below, as is relevant for our purpose: "2(.9 ') 'employee ' means any person em ployed for wages in or in connection with the work of a factory or establishment to which this Act applies and (i) who is directly employed by the principal employer on any work of, or inciden tal or preliminary to or connected 279 with the work of, the factory or establish ment, whether such work is done by the employ ee in the factory or establishment or else where; or (ii) who is employed by or through an immediate employer on the premises of the factory or establishment or under the supervi sion of the principal employer or his agent on work which is ordinarily part of the work of the factory or establishment or which is preliminary to the work carried on in or incidental to the purpose of the factory or establishment; or (iii) whose services are temporarily lent or let on hire to the principal employer by the person with whom the person whose services are so lent or let on hire has entered into a contract of service; The Calcutta Electricity Supply Corporation (India) Ltd., hereinafter referred to as the C.E.S.C. engages var ious contractors to carry out work of excavation, conversion of overhead electric lines and laying of underground cables under public roads, as well as for repair and maintenance of the aforesaid works.