“ James D. Maher, Esq., of the District of Columbia, is hereby appointed a commissioner to take and return the above-mentioned testimony, with the powers of a master in chancery as provided in the rules of this court. ”

“ The complainant shall thereupon be authorized to take the testimony of not exceeding three sanitary or engineering experts as specified in paragraphs 1 and 2, including such proof as they may elect to offer on the subject-matter covered by paragraph 3, the testimony relating to these subjects to be concluded on or before the fifteenth day of August next. ”