Margaret Knight, Inventor of Flat-Bottom Bag Machine

Margaret Knight is best remembered as the inventor of the machine that makes flat-bottomed paper bags.  This was a 19th-century innovation that still influences machinery today. However, that single achievement only scratches the surface of her story.  

Knight had a brilliant mind for mechanical problems, and she was confident in her abilities.  Early in her career, a machinist copied her invention and tried to patent it for himself. When Margaret Knight realized what had happened, she did not hesitate. She scraped together her money and hired a patent attorney to right the wrong.

To understand Margaret Knight, people need to recognize her for her creativity and her grit. She was a talented problem-solver who never stepped away from defending her accomplishments.

Growing Up

Margaret Knight (1838–1914) was born in York, Maine, the youngest of three children. Perhaps influenced by her two older brothers, she never played with dolls and loved crafting toys for herself and her brothers. She became known in the area for her superior kites and sleds.

The family was torn by the death of her father when Margaret was still a child. Margaret’s mother heard there was work in New Hampshire in the cotton mills, so the family moved there. Mrs. Knight and her boys took jobs at Amoskeag Manufacturing Company. When Margaret was 12, she joined them.

Mill Work

Margaret was at work on the line one day when a shuttle flew off its moorings. Shuttles are very sharp, and one flying loose was  dangerous. This one injured a woman working near Margaret.

Because Margaret witnessed the accident first hand, she was able to puzzle through what happened and why. She came up with two solutions—one that would keep the shuttle from flying off the loom; the other was a way to cover the tip of the shuttle to reduce the danger.

Knight approached management with her solutions on how to prevent another accident. The supervisor put Margaret’s idea into practice, and it made for a safer workplace. Margaret Knight was too young to know about patents then, so she did not profit financially from her extra work. However, the experience offered her an excellent education for the future.

Illness

While working at the cotton mill, Knight became ill and had to leave her job. There is no documentation as to what caused her illness, but many mill workers suffered from “brown lung” from the cotton dust and lint that blew around the factory. This caused workers to be prone to suffer chronic coughing, asthma, and severe respiratory failure.

Once she was feeling better, she looked for other employment. For a time, she worked at an upholstery shop and then moved on to a company specializing in photography.

Paper Bag Company

In 1867, Margaret Knight was living in Springfield, Massachusetts, and working at the Columbia Paper Bag Company.  Women were paid one-third of what male coworkers received, but she was glad for the work.

The factories at that time had simple machines that made V-bottom bags. Flat bottom bags were also made by the factory, but they had to be put together by hand.

Knight’s first job was as a bag bundler, tying up the machine-made envelope-style bags for shipping. From her vantage point at the end of the production line, she could see the workers guiding the simpler bags along from machine to machine. She also watched as another group—mainly women— painstakingly cut, folded, and glued what would be each flat-bottom bag. Because this labor-intensive process was so slow, flat-bottom bags were an expensive luxury item for merchants.

As Knight worked at her job each day, she also thought about how these processes could be automated.

Crafting Her Ideas

At the end of each day, she returned to her boarding house to test out what she felt would work. Her first invention was for a machine that improved on the V-bottom paper bag. For the patent, she called it a “paper feeding machine.” In 1870, she received a patent on that invention. She then applied her efforts to figuring out how a machine could be used to make a flat-bottom bag.

Working Model for Flat-Bottom Bag Machine

A few months later, she had a working wooden model that she was pleased with. Some who saw the device said it was “rickety,” but it cut, folded, and glued over 1,000 bags during her testing phase.

Just as she had done with her application for the “paper feeding machine,” Knight needed to find a mechanic’s shop where they could make her a working model in iron. She chose a machinist in Boston to help her.

The machine was extraordinarily complex, so in addition to leaving all her paperwork for the machinist, she checked in regularly to oversee what was being done.

Here’s How It Worked

The process starts with a roll of brown paper. A feeding mechanism draws the paper into the machine, where the paper is cut to size and then rolled into a tube.

Folding arms guide the edges of the paper inward to make a seam, along which a paste wheel applies adhesive. The paper is then pressed flat.

To create the flat bottom, special blades fold the sides of the paper inward. The top is left open and then the machine folds the two remaining flaps down over each other to create the flat bottom. As the folding arms move the flaps into place, glue applicators (timed by the machine’s gears) stamp onto the flaps the exact amount of adhesive to hold them shut. Finally, the completed bag is pushed through a set of heavy pressing rollers to firmly seal the glued bottom.

Ultimately, the finished bag is then ejected from the machine.

Margaret Knight clearly knew what she was doing. Her machines worked.

Knight’s Idea Stolen and Copied

During the time the machinist in Boston was working on Knight’s iron model, Charles Annan, another machinist, stopped in to visit. He noted what his friend was working on for Knight.

Annan saw the brilliance of what she developed, and he felt there was money to be made. He copied as many of the materials as he could and raced back to his own shop to make his own working model. He then submitted a patent application under his own name.  

When Margaret Knight received a message that her prototype was completed, she stopped by and picked it up. She brought with her the detailed paperwork she had prepared and took everything to the Patent Office.

Only then did she learn that someone had filed for the same device days ahead of her. 

But Charles Annan underestimated her. Knight was resolute, knowing full well who had put in the thousands of hours of sketching, problem-solving, and building to make the machine a reality. She was fully prepared to prove it though it would be costly. She scraped together what money she had and hired a patent attorney. She then sued Charles Annan for patent interference.   

Annan’s Defense

Annan claimed his device was somewhat different, and therefore, he deserved the patent. However, other sources noted that he told some people that he didn’t believe a woman possessed the mechanical ability to conceptualize such a complex machine.

Knight was a meticulous worker and had complete documentation of all the steps she took in creating her invention. She gathered her early journal entries and detailed mechanical drawings. She also gathered testimonies from everyone from the people in her rooming house to the machinists who built her prototypes.

The court case took 16 days, proving very costly for Knight, but she was determined. Ultimately, the judge for the patent office ruled in her favor. Charles Annan’s patent was thrown out, and Margaret Knight was rightfully granted the flat-bottom paper bag machine.

Knight’s machine was an important invention. It turned the flat-bottom paper bag from an expensive, hand-crafted luxury into the cheap, disposable basic bags we use today.

Knight’s Company Already Making Bags

In 1870—before her patent was granted–Margaret Knight and a business partner set up Eastern Paper Bag Company to make the bags. Knight overcame resistance as a factory boss because workers saw that she had complete command of the machinery and the factory process.

Once she received her patent, Knight made a new arrangement with her business partner. She asked for a royalty on the profits (capping her take at $25,000). The business partner was left to run the factory, and Knight was free to focus on inventing.

More Work Ahead for Margaret Knight

Her 1871 patent victory was just the beginning of a long, prolific, and highly unusual career for a woman in the 19th and early 20th centuries. She spent the rest of her life as a full-time, professional inventor.

She rented space in Framingham, Massachusetts. This gave her a place to experiment with what she was working on. Most of her devices had to do with manufacturing. One was a machine for boring holes, another was for a numbering machine, and yet another pertained to making windows and sashes. These were the types of challenges that interested her.

But Framingham was the seat of shoe manufacturing, so she heard new stories and wondered about ways to improve shoemaking. Between 1883 and 1894, she received six patents for massive, complex shoe-manufacturing machines. These included devices for cutting shoe soles and stitching different parts of the shoe together, which helped further automate another major American industry.

Automotive Industry

The automotive industry was making progress in the early 20^th century, and though Knight was in her 60s by this time, she paid attention to what was happening there.  Between 1902 and 1914, she designed and patented several components for internal combustion engines and rotary motors. She also patented a sleeve-valve automobile engine, a motor drive, and a compound rotary engine.

It was virtually unheard of for a woman of her generation—let alone one in her 70s—to be designing heavy automotive engines.

Fame Much Later

Margaret Knight passed away in Framingham in 1914. She was 76 At her death, she held patents for 22 inventions and had assigned patents for an estimated 60 more to her employers or financial backers.

Margaret Knight never cared about being interviewed or photographed for her inventions. She was always thinking about her next challenge, so the lack of recognition probably didn’t bother her.

But she was too talented to ignore. In 2006, she was posthumously inducted into the National Inventors Halls of Fame for her flat-bottom paper bag machine (Patent No. 116,842).

And the Smithsonian Institution has permanently preserved her working model of the paper bag machine. This is an honor afforded to only a few inventions of the 19^th century.

Margaret Knight is often remembered for one particular invention, but the true acclaim she deserves lies in her brilliant, problem-solving mind, her tenacity, and her indomitable spirit. She was far more than the creator of a single machine; she was a visionary who never backed down from a challenge. The work she did resulted in automating many businesses.

Share with Others!