(6) public documents of any other class in a foreign country,-- by the original, or by a copy certified by the legal keeper thereof, with a certificate under the seal of a Notary Public, or of 1[ an Indian Consul] or diplomatic agent, that the copy is duly certified by the officer having the legal custody of the original, and upon proof of the character of the document according to the law of the foreign country. PRESUMPTIONS AS TO DOCUMENTS