(1) At a convenient time before the sitting of the Court at which a jury is required, the sheriff shall select—
(a) in the case of the trial of capital offences, not less than 30 persons; and
(b) in any other case not less than 20 persons,
whose names appear in the Jurors' Book, taking one from the top and one from the bottom of the list alternately, and shall so proceed from time to time, commencing each time from where he or she last left off, until every person has been summoned in his or her turn.
(2) When selecting from the new Jurors' Book compiled for each year, the sheriff shall begin with the names on the list next following or preceding in alphabetical order, the names of the persons who were last taken in the preceding year, or as near thereto as circumstances may permit.