The 30th section of the judiciary act of 1789 gives authority to this court to compel witnesses to attend before a commissioner for examination de bene esse, in the same manner ás to compel them to appear and testify in court. And, upon due proof of service of a subpoena upon a witness, requiring his attendance before a commissioner, and the certificate of the commissioner that • the witness did not attend before him, it is proper that an attachment should issue against the witness. But that statute does not apply to a witness who is casually absent from home, although he is found at a place • more than one hundred miles from the place of trial of the cause, unless he is about going to sea, or is aged, infirm, &c. In the present case, the contempt of court imputed to the witness in disobeying the subpoena is purged. He could not rightfully be subjected to an examination de bene esse under the statute. The question of the authority of the commissioner and of the regularity of the proceedings before him, *873is properly brought before the court by affidavit, and the witness must be discharged from the attachment.