Pacific Mail straight line handstamps are always in demand. They are the names of the steamships the company used. No one knows what types of documents these were used on, as there are no known examples of these still on document. The speculation is that these were on passage tickets. Since those all were sent overseas, that is why none have been found. Until one is found on document, we won't know for certain.
A simplistic valuation model would go as follows:
Below are the examples I currently have in my collection.
If you have any examples that I don't have for sale or trade, please send high-resolution images and asking price to info@revenue-collector.com.
None in my collection. If you have one for sale or trade, please email me.
None in my collection. If you have one for sale or trade, please email me.
None in my collection. If you have one for sale or trade, please email me.
None in my collection. If you have one for sale or trade, please email me.
None in my collection. If you have one for sale or trade, please email me.
None in my collection. If you have one for sale or trade, please email me.
From the font we can tell that it is a Pacific Mail Steamship Co. cancel, but no way to know for certain which one... based upon the width of the serifs at the base of A, I would speculate ALASKA (the serifs at the base of the A in ARIZONA are not as wide, at least based upon the examples in my collection).
Mixed-ship items are exceptionally rare. There are only a handful known.