68X. Service of notices and orders .—Any notice or order issued or made unde r this Chapter shall be served—
(a) by tendering the notice o r order or sending it by regis tered post to the person for whom it is intended or to his agent;
(b) if the notice or order cannot be served in the manner provided in clause (a), by affixing it on a conspicuous place in the property in relation to which the notice or order is issued or made or on some conspicuous part of the premi ses in which the person for who m it is intended is known to have last resided or carried on business or personally worked for gain.