(a) During the annual encampment, and on every duty on parade ordered by the Commanding General, there shall be allowed and paid for each day of service:
(1) To each member of the regularly enlisted bands, $4;
(2) To the chief musicians, $8; and
(3) To the principal musicians, $6.
(b) In the event there is no enlisted band or field music, or not a sufficient number of either, the Commanding General may authorize the employment of such as he may deem necessary for the occasion; provided, that the total pay of the enlisted musicians shall not in any event exceed the rates authorized by this section.