How the Revolving Door Was Invented

The 1888 patent for the revolving door, designed to keep buildings warm while allowing people to enter and exit easily.

What it covers

The patent describes a central vertical shaft with radiating wings that rotate within a circular enclosure. This mechanism creates a continuous seal between the outside and inside of a building. By maintaining this seal, the door prevents cold drafts from entering and warm air from escaping, which was a significant improvement over traditional swinging doors that let in large gusts of wind every time they opened.

What it doesn't cover

• —Does not cover automatic or motorized revolving doors
• —Does not cover sliding or traditional hinged door mechanisms
• —Does not cover security-focused revolving doors with anti-tailgating sensors

The clever bit

The genius lies in the 'always-closed' design; the door is never fully open to the outside, effectively acting as an airlock for pedestrians.

Why it matters

Before this invention, opening a door in a busy building during winter caused massive heat loss and uncomfortable drafts. The revolving door became a staple of urban architecture, allowing large public buildings and hotels to maintain climate control while handling high foot traffic.

Real-world examples

• 1.Standard revolving doors in hotel lobbies
• 2.Office building entrances
• 3.Department store revolving entryways