A built-in sunroom was created within a bay window adjacent to the library (historically the dining room). Not many homes were built with such a room in the late 1860s. The room was used to keep plants. Many of the plants currently displayed were popular during the 19th Century - especially the Boston Fern and the Geranium. The slatted floor allowed watering plants without having to worry about cleaning up a wet floor. There is also a vent in the roof, which would have been operated by pulleys and used to adjust temperature levels and provide ventilation for the plants. Oddly enough, the slatted floor was discovered during the 1970-72 restoration of the Dow House when flooring had to be removed. Th solarium floor had been covered over so that the room could be used for other purposes most likely during the 1920s when the Dow House was converted to apartments.