A box-head window looks like a typical double-hung window, but both the upper and lower sash fully retract into a pocket above the window.

I’ve repaired countless antique double-hung windows and pocket doors over the decades but had never laid eyes on a pocket window until a few months ago, when I was hired to tune up the windows in an early 20th-century Dutch colonial. Those in the main part of the house were the typical double-hung variety that simply required smoothing and waxing friction surfaces, lubricating pulleys, and restringing a few sash weights to enable them to operate with the touch of a finger.

The porch was a different story. It was enclosed by a dozen double-hung windows that looked exactly like the others … until I lifted one of the few operable sashes and watched it disappear completely into the wall above. Back when all 12 of these units worked properly, this ingenious design would have empowered the homeowners to transform their porch from indoor to outdoor space—or vice versa—within a minute. And what’s more: If uninvited pests flew in to spoil the party, drop-down insect screens (permanently housed in each overhead compartment) could have been deployed just as quickly.

Even the metal screens of a box-head window retract fully.

This three-in-one window transformer was the brainchild of Edmund H. Lunken, a manufacturer from Cincinnati. Although Lunken never claimed to have invented the pocket (or box-head) window concept, he was awarded numerous patents for his innovations, such as the skinny, two-piece nested screen and thinner, steel-reinforced sashes that afforded space for the screens without requiring thicker walls. He also patented an effective means of weatherstripping the upper sash and lower screen to seal the pocket from air infiltration.

A patent for E.H. Lunken's window design was issued in November 1918.
By 1920, the Lunken Window Company of Cincinnati, Ohio was advertising their windows nationwide.

These patents were issued between 1916 and 1918; by 1920, the finished products were advertised for sale, and when these state-of-the-art showpieces were installed on a certain porch in Western Connecticut, they must have been the talk of the town. Sadly, by the time I arrived in the summer of 2023, only 11 out of 48 cords were intact and those were as stiff and faded as the broken ones. It was plain to see that these magnificent 100-year-old windows had fallen into disuse simply because nobody knew how to restring them.

Much like so many of Frank Lloyd Wright’s masterpieces that didn’t age well, Edmund Lunken’s invention was both ingenious and a nightmare to maintain. The poor soul sent in to replace the first broken sash cord—decades after the windows were installed and long after the owner’s manual had disappeared—would have encountered three stiff challenges: no access panel cut into the frame; a permanently fixed metal parting bead that did not allow removal of the “upper” sash from inside; and pulleys mounted high up inside the pocket and difficult to access.

Fortunately, I discovered that Lunken had left a trail of breadcrumbs, in the form of brass screws—some of them decorative—to identify particular stops and other components that were designed for disassembly. I ultimately had to remove a total of nine pieces before I was able to get my hands on the first of many pairs of unstrung cast-iron weights. It was also my good fortune to have arms long enough for my fingers to touch the pulleys at the top of the pocket. With practice, I was able to coax a fishing sinker, with a new cord attached, over the pulley and down to the sash weight. After 48 successful restringings, plus the standard tuneup work, all 24 of Lunken’s sashes go up, down, or out of sight with the greatest of ease.

After the author completed his work, the sashes were fully functional in the 12 box-head windows that enclose this porch.

Photos by Tom O'Brien.

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