In any suit the plaintiff or defendant by leave of the Court may deliver interrogatories in writing for the examination of the opposite parties or any one or more of such parties and such interrogatories when delivered shall have a note at the foot thereof stating which of such interrogatories each of such person is required to answer: Provided that no party shall deliver more than one set of interrogatories to the same party without an order for that purpose: Provided also that interrogatories which do not relate to any matters in question in the suit shall be deemed irrelevant, notwithstanding that they might be admissible on the oral cross-examination of a witness.