Every process issued by a Collector under this Act shall be under the seal and signature of the Collector, and shall be served or executed by the Nazir or by such other Officer as the Collector may direct at the cost of the party at whose instance it issued. The amount of such cost, and, in the case of summons to a witness, any sum required for the travelling expences of such witness, shall be deposited in Court before the process is issued. Provided that if in any case the Collectors is satisfied that a party is unable to pay the cost of any necessary process, he may direct such process to be served free of charge.