Here's the explanation: "At her death, she held patents for 22 inventions and had assigned patents for an estimated 60 more to her employers or financial backers."

https://americacomesalive.com/margaret-knight-1838-1914-successful-inventor/

These posts reference a total of 87 patents attributed to Knight:

https://framinghamhistory.org/the-mystery-of-margaret-knight/#:~:text=In%201912%2C%20at%20the%20age,death%20was%20valued%20at%20%24300.

https://m.facebook.com/lottiedolls/photos/margaret-e-knight-is-one-of-the-most-productive-american-inventors-who-became-kn/5043119422397154/

https://www.thomasnet.com/insights/4-female-inventors-who-revolutionized-industry-and-technology/

Here's an engraving showing a device for making conical-shaped paper bags.

From Smithsonian Magazine:

"Not only did Knight file for a patent, she rigorously defended her ownership of the bag machine idea in a legal battle with a fraud who had copied her. Having gotten a glimpse of Knight’s machine in its development phase, a man named Charles Annan decided he would try to pull the rug out from under her and claim the creation as his own.

This turned out to be extremely ill-advised, as Knight, who spent a large chunk of her hard-earned money on quality legal counsel, handed Annan a humiliating courtroom drubbing. In response to his bigoted argument that no woman could be capable of designing such a machine, Knight presented her copious, meticulously detailed hand-drawn blueprints.

Annan, who had no such evidence to offer himself, was quickly found to be a moneygrubbing charlatan. After the dispute was resolved, Knight received her rightful patent, in 1871."

From National Inventors Hall of Fame (inducted in 2006):

"Margaret Knight invented a machine that could automatically cut, fold, and glue flat-bottomed paper bags. Knight's invention revolutionized the paper bag industry by replacing the work of thirty people with one machine.

Born in York, Maine, Knight went to work in a New Hampshire textile mill following her father's death when she was still a child. After witnessing a serious accident caused by a malfunctioning loom, Knight was inspired to create her first invention, a safety device that became a standard fixture on looms. That device was the first of many technical innovations that would touch a wide range of industries.

Before Knight invented her paper-bag machine, flat-bottomed bags could only be made manually and at great expense. With her innovation, flat-bottomed bags could be mass manufactured, replacing less useful v-shaped bags. Her invention was used worldwide. An updated variation of her machine was still in use at the end of the twentieth century.

Knight founded the Eastern Paper Bag Company in Hartford, Connecticut. Between 1870 and 1915, the inventor was granted patents for at least twenty-six inventions, ranging from a window frame, to a sole-cutting machine for shoemaking, to a compound rotary engine."

There is a documentary biography from 2013 called Afternoon of a Faun (no clue if this is still available), directed by Nancy Buirski.

According to The Master's Muse by Varley O'Connor (albeit a novelization of Le Clercq's life), "[t]here wasn't enough vaccine in 1956. Only the youngest dancers in the company" were innoculated before they went abroad on their 10-week European tour beginning in August 1956. After Le Clerq contracted polio and was confined to an iron lung in a hospital in Copenhagen on November 1, 1956 (which made international news), the American Embassy arranged to fly in enough of the vaccine for 50 dancers and they all returned healthy to New York at the end of the tour on November 12, 1956.

Source:

When Le Clercq "was 15 and a prodigy in Balanchine’s school, he made a ballet called 'Resurgence' on her and some fellow students for a March of Dimes benefit at the Waldorf-Astoria. The music was Mozart’s String Quintet in G minor, and at the close of the plangent adagio, Balanchine, as the Threat of Polio, came onstage wearing a large black cape and enveloped her; she sank to the floor. In the final movement — a sunny allegro — she reappeared in a wheelchair, children tossed dimes, and she rose and danced again. What at the time was a simple exercise in entertaining a charity audience acquired in retrospect the weight of an omen or a hex. Balanchine, who was deeply mystical, was haunted by the notion that he had somehow brought on her fate."

I love Le Clercq's attitude: "[S]he was mystified when people told her they admired her courage. To hear her tell it, she had just gone on. In fact, just going on required a choice. She once told me it took her 10 years to decide not to commit suicide. 'And then,' she said, 'I was fine.' ... It was not, in truth, all downhill after the polio. Life after dancing wasn’t less or worse, just different. When in 1984 a documentary about Balanchine was broadcast on television, she saw clips of herself dancing. I asked if that was hard. She said no — by that time she’d been sitting longer than she’d been standing, and besides, the friends she had danced with were retired, so they weren’t dancing anymore, either."

Pretty incredible that Van Damme was able to do this, let alone at age 53.