The headquarters of the various districts are located in the large cities, where the greatest number of aliens apply for naturalization, and in the public buildings or in close proximity to the courts.[64] In many of the cities where the examiners are in the same building with the court, it is the practice of the alien to appear with his witnesses first in the office of the chief examiner. Here an examination is made in advance of any work in the office of the clerk of court. The examiners, specially trained in the work, first ascertain whether the alien arrived in the United States prior to the passage of the Act of 1906. If he arrived prior to the passage of the Act, the examiner then ascertains, before assisting him in taking the second step in the process of naturalization, whether the alien has a declaration of intention that has matured.[65] If he has arrived subsequent to the passage of the Act, he ascertains whether the alien has been notified by the Bureau that the certificate of arrival required by law to be filed with the clerk of the court at the time of filing the petition for naturalization has been placed there by the Bureau. It may be stated here that when an alien applies for a certificate of arrival, the Bureau notifies him when it has been obtained and forwarded to the clerk of the court selected by the alien in which to file his petition for naturalization, and he is directed to proceed with the filing of his petition at the earliest practicable moment. Upon learning that the certificate of arrival has been obtained, the examiner interrogates the candidate to learn his qualifications for citizenship and records the results of his examination. He then examines the witnesses to be reasonably certain that they are American citizens, that they are credible and of good character, that they have personally known the applicant for the statutory period, and can intelligently testify both as to his residence and good behavior during the period required by the statute to be ascertained and shown to the satisfaction of the court. The examiner also sees that the blank form furnished by the Bureau for setting forth the statements required to be embodied in the petition for naturalization is correctly prepared. When the examiner finds affirmatively in all of these respects, he marks the filled-out blank with his initials and sends it with the petitioner and his witnesses to the office of the clerk of the court, where nothing further is to be done than the simple clerical work of filling in the petition, original and duplicate, from the blank, securing the signatures and affidavits of the petitioner and his witnesses, filing the triplicate copy of the declaration of intention and the certificate of arrival with the petition, and notifying them as nearly as may be of the date of the hearing.