In case it shall appear to the satisfaction of any magistrate that the attendance of any witness whose testimony may be required in any case before him cannot be had (a) by reason of (i) extreme age, (ii) sickness or infirmity or (iii) indispensable absence on public official duty, (b) in consequence of intended removal from the State before the cause can be otherwise ready for trial or (c) when such witness may be resident in another county or without the limits of the State, such magistrate may take the examination of such witness in writing or cause it to be done by another magistrate or other officer authorized by law to administer oaths, to be used in evidence on the trial of the case. But the parties to such cause shall have notice thereof in time to be present if they or either should choose to be present or notice may be given by either party to the other of interrogatories to be propounded to such witness, with four days’ time given the party notified to prepare cross-interrogatories, upon which interrogatories and cross-interrogatories, when preferred by the parties or either of them, the deposition shall be had. When such examination is so made by another, it shall be sealed up, with the title of the case endorsed, and conveyed by a disinterested person to the magistrate authorizing it or mailed and the postage prepaid.