Load bearing walls in 1860s house
You'll need an onsite review by a structural engineer to determine the answer.

Old houses can and are framed in many different ways and there are no rules (unless this house has been updated with pre-manufactured trusses). Often ceiling joists bear on walls when the roof rafters do not. Also, there are often intermediate framing members for bracing of the roof rafters that bear on walls, and there is no pattern and at times can be almost random. Further, the roof members will not 'calc out' meaning that they surely will be considered undersized when using current material strengths, properties and codes, and you do not want to do anything that increase the load or decreases the strength.  

A structural engineer will review all the available information and give you the answer. I suggest hiring a smaller firm for better fee rates.