When, in the opinion of the court, it is proper that the jury should view the place in which the offense is charged to have been committed, or in which any other material fact occurred, it may order the jury to be conducted in a body, in the custody of the sheriff, to the place, which must be shown to them by a person appointed by the court for that purpose; and the sheriff must be sworn to suffer no person to speak or communicate with the jury, nor to do so himself, on any subject connected with the trial, and to return them into court without unnecessary delay, or at a specified time.