How Margaret Knight's Machine Made Flat-Bottom Paper Bags
This 1871 patent by Margaret Knight describes a machine that automatically folds and glues paper to create flat-bottom bags, a major improvement over earlier V-shaped designs.
Original patent title: “Improvement in paper-bag machines”
This 1871 patent by Margaret Knight describes a machine that automatically folds and glues paper to create flat-bottom bags, a major improvement over earlier V-shaped designs. Granted to Margaret E. Knight in 1871.
Key facts
Coverage
What does this patent actually cover?
Based on the patent title, this invention describes a machine designed to improve the manufacturing of paper bags. Historically, Margaret Knight's work focused on creating machinery that could automatically produce flat-bottom paper bags, a significant advancement over earlier V-shaped bags or those requiring manual finishing. While specific claimclaimA numbered sentence at the end of a patent that legally defines what the inventor owns. The most important section.Read more → details are unavailable for this patent (US 116842), the core mechanism likely involved a system for folding and gluing paper to form a stable, rectangular bottom. This allowed bags to stand upright and hold more contents efficiently. For example, a grocery store could use bags from this machine to pack items, knowing they wouldn't tip over easily.
The gap
What does this patent NOT cover?
- Does not cover machines that produce V-shaped or pointed-bottom paper bags.
- Does not cover methods for manually constructing paper bags.
- Does not cover machines for making bags from materials other than paper, such as plastic or cloth.
- Does not cover machines that only print on paper bags without forming them.
- Does not cover machines for making bags with handles, as the focus is on the bottom-forming mechanism.
These exclusions are unique to PatentBrief — derived from the actual claim language, not patent-office boilerplate.
What made this novel
The clever bit was automating the creation of a flat, square bottom for paper bags. Before this, bags often had V-shaped bottoms or required tedious hand-folding to stand upright. Knight's machine made the flat bottom efficiently, making bags far more practical for carrying goods.
The Patent Drawing
Schematic visualization of the patent's claim structure. Hand-drawn diagrams in progress for each landmark patent.
Where you've seen this
Real-world examples
Most modern paper grocery bags
Paper bags used in retail stores
Lunch bags
Takeout food bags
Why it matters
The bigger picture
This patent is historically significant as it represents a key invention by Margaret Knight, a pioneering female inventorinventorThe person who actually conceived the invention. Listed on the patent regardless of who owns it.Read more →. Her machine revolutionized the paper bag industry by enabling the mass production of flat-bottom bags. These bags were far more practical and durable than previous designs, making them essential for retail and grocery stores and changing how goods were packaged and carried.
Granted
July 11, 1871
Market context
Who's building on this
Companies in this space
Modern packaging companies and manufacturers of industrial machinery continue to build on the principles of automated bag production. Companies like Windmöller & Hölscher, B&B-Maschinenbau, and Newlong Industrial manufacture sophisticated paper bag making machines that incorporate advanced versions of the fundamental mechanisms for forming, folding, and gluing.
Market impact
This patent's invention created the foundation for the modern paper bag industry. It enabled the mass production of a highly functional and practical item, directly impacting retail and grocery sectors. The ability to efficiently produce flat-bottom bags allowed stores to package goods more effectively, contributing to the growth of consumer commerce and setting a standard for packaging that persists today.
Claim 1 — Plain English
What this patent covers
Based on the patent title, this invention describes a machine designed to improve the manufacturing of paper bags. Historically, Margaret Knight's work focused on creating machinery that could automatically produce flat-bottom paper bags, a significant advancement over earlier V-shaped bags or those requiring manual finishing. While specific claim details are unavailable for this patent (US 116842), the core mechanism likely involved a system for folding and gluing paper to form a stable, rectangular bottom. This allowed bags to stand upright and hold more contents efficiently. For example, a grocery store could use bags from this machine to pack items, knowing they wouldn't tip over easily.
The clever bit
The clever bit was automating the creation of a flat, square bottom for paper bags. Before this, bags often had V-shaped bottoms or required tedious hand-folding to stand upright. Knight's machine made the flat bottom efficiently, making bags far more practical for carrying goods.
What it does not cover
- Does not cover machines that produce V-shaped or pointed-bottom paper bags.
- Does not cover methods for manually constructing paper bags.
- Does not cover machines for making bags from materials other than paper, such as plastic or cloth.
- Does not cover machines that only print on paper bags without forming them.
- Does not cover machines for making bags with handles, as the focus is on the bottom-forming mechanism.
PatentBrief Score
Impact Score
Limited data
Citation count
0/40
No citations yet
Claim breadth
0/20
Narrow claimsclaimsThe numbered statements at the end of a patent that legally define what the inventor owns.Read more →
Recency
0/20
Older than 20 years
Assignee scale
0/20
Independent or smaller assigneeassigneeThe entity that owns the patent — usually the inventor's employer or a company.Read more →
PatentBrief Impact Score — based on citation count, claim breadth, recency, and assignee scale. Not a legal assessment.
Heuristic Value Estimate
What this patent might be worth
$1K – $4K
Midpoint $3K · expired or expiring · industry ×0.9
Heuristic only — blends forward/backward citation counts, claim scope, time remaining, litigation history, and CPC-derived industry baseline. Real valuations need a professional appraisal.
Concepts involved
Cite this patent
(1871). How Margaret Knight's Machine Made Flat-Bottom Paper Bags (U.S. Patent No. 116,842). U.S. Patent and Trademark Office. https://patentbrief.org/patent/us/116842/paper-bag-machine-knight
Auto-generated from the patent record. Double-check author order and the issue date against the official USPTO document before submitting.
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Common Questions
Frequently Asked Questions
What does How Margaret Knight's Machine Made Flat-Bottom Paper Bags cover?
This 1871 patent by Margaret Knight describes a machine that automatically folds and glues paper to create flat-bottom bags, a major improvement over earlier V-shaped designs.
Who owns patent US 116842?
Margaret E. Knight owns this patent, granted in 1871.
When does this patent expire?
This patent has expired and is now in the public domain — anyone can use the invention freely.
What problem does this patent solve?
This patent is historically significant as it represents a key invention by Margaret Knight, a pioneering female inventor. Her machine revolutionized the paper bag industry by enabling the mass production of flat-bottom bags. These bags were far more practical and durable than previous designs, making them essential for retail and grocery stores and changing how goods were packaged and carried.
What does this patent NOT cover?
Does not cover machines that produce V-shaped or pointed-bottom paper bags.
Patent monitoring