Windows in windmill towers

Windows are a notable feature that appear in a variety of locations, shapes, and sizes in some windmill towers. While not providing human access like the other primary windmill tower openings, windows provided ventilation and light to the mill’s interior. (Hearths may also have provided light.)

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Placement of the windows in the windmill tower

Windows face either east or west and never to the north or south, placed either directly above the main opening or directly opposite it. In numerous windmill towers, windows facing east are at the level of the main working floor. Notable exceptions to this low placement of the windows are the windows in the upper levels of the windmills at Body Slob (KQ), Clifton Hill (KQ), and Bonne Esperance (QQ). In significantly fewer numbers, windows facing west were invariably built on the upper floors. Notable examples at Boetzberg (EA) and Green Kay (EA) also include a window facing east at the working floor level.

Interior of windmill showing a window. Above the window are 8 vertical slots described in the caption. Bricks above the masonry support a wooden rail on which the mill cap would turn. Two parallel beams visible with a connecting piece that has fallen out of place. The Bonne Esperance window sits well above the working floor, between the 2 upper floors.

Ventilation and light provided by aesthetically trimmed windows

Windows in the windmill towers generally have a smaller exterior than interior area, creating a pressure differential that draws air into the windmill. This indicates that windows were designed for ventilation, understandable given the heat generated by the rotating machinery and the warm, tropical climate. East-facing windows would naturally catch the breezes that propelled the windmill sails.

Windows also provided light. Windows facing east at the working floor illuminated the back side of the rollers. Since the cane typically was hand fed on the backside for the second crushing between the bagasse and king rollers, having extra light may have facilitated this task.

West facing windows provided light in the darker upper reaches of the mill. Round windows facing west had decorative purposes in the mills at Salt River (NB), La Reine (KQ), Green Kay (EA), and Boetzberg (EA). In addition to providing ventilation & light, aesthetic treatment suggests that they were also for decorative purposes, especially in the examples of La Reine and Green Kay.

The Green Kay windmill as viewed from the west featuring the main entrance, inscription stone, and window above it. Green Kay windmill windows above and opposite the main entrance. The round window’s trim reflects the aesthetic trim around the other openings.

East-facing windows often had a square exterior appearance; on the interior, the bottom was squared with a flaring arch above to induce the passage of air from the interior to the exterior. This presented a neat exterior appearance, underlining the aesthetic importance apparently placed on the appearance of plantation structures.

Close up of square window with a raised keystone, indicating the window is original to the mill. Clifton Hill square window exterior mill is fairly high, between the two upper floors.

Buttoning up the windmill

Windows could be closed. One example is at Wills Bay (NA). In this case, openings that could accommodate boards across the window are found at a variety of heights. Boards could be used to close the mill, secured in these slots. Another example is the survival of metal hinges by the window at Body Slob (KQ), indicating a shutter that opened to the outside.

When were windows included in windmills?

Windows were far more common in later mills, although some early mills have windows. None of the earliest three windmills, built by 1749, had any windows. Few windmill towers built in the 1750s and 1760s incorporated windows. Notably, the windows in the windmills constructed at earlier dates all appear to have been on the east side of the mill at the working floor. This being said, the round, west-facing windows cannot be assigned to a particular period of mill construction. As examples, La Reine‘s mill was built by 1766 while the mill at Boetzberg was built after 1794.

Boetzberg windmill interior looking west. Boetzberg windmill two round windows provided light and ventilation for the top 2 floors of the mill, helpful during maintenance work.