SECTION 1. Section three of Act Numbered Five hundred and eighty-one, entitled "An Act to provide for the revision of the assessment upon real estate in the city of Manila," enacted January eighth, nineteen hundred and three, is hereby amended by substituting in lieu thereof the following:
"SEC. 3. The Board of Tax Revision shall hear such evidence as it may deem wise as to the value of the property, including the rental income therefrom, and shall personally, so far as seems necessary, view the lands and improvements, the value of which is under consideration. The Board is hereby empowered in case of the failure of a witness duly summoned to appear before it, to attend, to cause to lie issued a warrant to arrest such witness and bring him before the Board.
"The members of the Board of Tax Revision and the secretary thereof are authorized to administer oaths to witnesses before said Board. In the event that a witness brought before the Board shall refuse to answer questions propounded to him by the Board, or any member thereof, the Board is empowered to direct such witness so refusing to answer to be taken before the municipal court of the city of Manila, where, in the event of his still refusing to answer questions, and if the Court shall doom such questions proper and competent and within the reasonable scope of the powers of the Board of Tax Revision, he shall be dealt with as if a witness before said court.
"The City Attorney shall be the legal adviser of the Board and subject to calls by the Board in matters pertaining to the exercise of its functions."