(a) The witnesses at the hearings shall be examined viva voce, but the Board may, at any time, for sufficient reason, order that any particular facts may be proved by affidavit or that the affidavit of any witness may be read at the hearing, on such conditions as it may think reasonable, or that any witness whose attendance ought, for some sufficient reason to be dispensed with, be examined before a member of the Board. The evidence taken before a member of the Board shall be confined to the subject matter in question, and any objection to the admission of evidence shall be noted by the member and dealt with by the Board at the hearing. Such notice of the time and place of examination as is prescribed shall be given to the parties. All examinations shall be returned to the Board, and may without further proof be used in evidence, saving all just exceptions.
(b) The Board may, whenever it deems it advisable to do so, require written briefs to be submitted by the parties.
(c) The hearing, when once commenced, shall proceed, so far as in the opinion of the Board may be practicable, from day to day. [Rule 10]