Section 4. Validity. —

A chattel mortgage shall not be valid against any person except the mortgagor, his executors or administrators, unless the possession of the property is delivered to and retained by the mortgagee or unless the mortgage is recorded in the office of the register of deeds of the province in which the mortgagor resides at the time of making the same, or, if he resides without the Philippine Islands, in the province in which the property is situated: Provided, however, That if the property is situated in a different province from that in which the mortgagor resides, the mortgage shall be recorded in the office of the register of deeds of both the province in which the mortgagor resides and that in which the property is situated, and for the purposes of this Act the city of Manila shall be deemed to be a province.