1907 Philippine Constabulary Envelope
1906 Dagupan "NORTH" Railroad Post Office Postmark
1907 OCTOBER 7: DAGUPAN to MANILA
1c Franklin on Philippine Constabulary penalty envelope tied with
DAGUPAN & MANILA R.P.O. / NORTH postmark with RMS
(rail mail service) duplex. 

This postmark, applied on board the train, is very elusive since it is seldom that a letter addressed to Manila or elsewhere is mailed on a train that is heading to the provinces. 

A MUST FOR A PHILIPPINE SPECIALIST

eBay, $256.00