For 112 years, the house has been cooled primarily by opening the windows (along with the occasional window A/C unit).  We now have two low-profile evaporative coolers mounted on the roof.  The one located by the chimney will have duct work to each of the four bedrooms in the main part of the house and the other unit over the apartment will simply open up into the upstairs hallway, providing cooling for the apartment bedrooms as well as the first floor.