25 Pa. Stat. § 3330
Every witness subpoenaed attending the trial of any contested election of the first class, shall be allowed six cents for every mile of the distance necessarily traveled by him in coming to and returning from the place of trial, and shall also be allowed the sum of two dollars and fifty cents for every day he may be detained at the place of such trial, which mileage and expense, as well as the expense of summoning such witnesses, shall be taxed by the select committee and certified by their chairman to the Speaker of the House of Representatives or the presiding officer of the Senate, or both, as the case may require. The amount thereof, after having been first approved by the house or houses to which such certificate may be made, shall be paid by the treasurer of the county or counties in which the facts complained of took place, if such facts be substantiated, or by the treasurer of the county or counties in which the petitioners shall reside, if the statements in the petition shall not be substantiated, on orders drawn by the Speaker of the House of Representatives or the presiding officer of the Senate, or both, as the case may require.
25 P.S. § 3330