Pre 1860 Disston no. 12 panel saw.  It has a  26-inch plate with decrative conical nuts and rosewood handle.  Disston used conical nuts before he started using medallions and before split nuts were invented.  The last pictures show Disstons bolt pattern with conical nuts and also the shape of the handle . There looks to have been a preventative repair on the bottom of the handle, but there are no visible cracks.  One of the rear nuts is sadly missing.  The handle is in really good shape for its age, and there is no pitting on the saw plate.  I've looked at this plate in every kind of light imaginable, and I can't see even a hint of an etch. It's filed cross cut and 8.5 ppi.