Section 567
the defendant is a public officer (not belonging to the 5 [the Indians] military 6 [naval or air] forces 7 ***), or is the servant of a railway company or local authority, the Court may, if it appears to it that the summons may be most conveniently so served, send it for service on the defendant to the head of the office in which he is employed, together with a copy to be retained by the defendant.