On this day in history, June 10, 1752, Benjamin Franklin is
reported to have flown a kite during a thunderstorm, with
a goal of collecting ambient electrical charge in a Leyden
jar — a container that could store an electrical charge for
later use.

This potentially would enable him to demonstrate the
connection between lightning and electricity.

Franklin showed an interest in the subject of electricity in
the mid-1740s when much was still unknown on the topic.

For almost a decade he conducted electrical experiments.
(History.com.)

A Leyden jar was the original form of the capacitor
(also called a condenser).      

Leyden jars are still used by teachers today to
demonstrate the principles of electrostatics.