What key innovation allowed the ballpoint pen to dispense ink without capillary action or gravity feed?

Answer

A tiny, free-rolling ball resting in a socket

The key mechanism was the ball-and-socket design, where the rolling ball dispensed the viscous ink. This also shielded the ink from the air, preventing evaporation.

What key innovation allowed the ballpoint pen to dispense ink without capillary action or gravity feed?
inventionHistorypenwriting instrument