(a) A judgment that the defendant pay a fine, or a fine and costs, may also direct that he be imprisoned until the same is satisfied, specifying the extent of imprisonment which shall not exceed one day for each two dollars of the fine, or fine and costs. In no event shall the extent of such imprisonment exceed six months.
(b) When an indigent prisoner, sentenced under subsection (a) of this section to pay a fine, or a fine and costs, with or without imprisonment, has been confined in prison thirty days, solely for the nonpayment of the fine, or fine and costs, he may make application in writing to the Board of Parole, setting forth his inability to pay the fine, or fine and costs. If after such investigation as the Board of Parole deems necessary in each case and on examination of the reasons set forth in said application and evidence which may be offered in support of and against the same it appears to the Board of Parole that such convict is unable to pay such fine, or fine and costs, and that he has not any property exceeding thirty dollars in value except such as is by law exempt from being taken on execution for debt, the Chairman or Acting Chairman shall administer to him the following oath: