Lighting rods

lightning rods.

 It is a metallic object mounted on top of a building. If a lightning falls to a building, with the lightning rod the lightning passes through the building and it doesn't produce damages. Lightning rods are called finials,air terminals or strike termination devices.
Lightning rods were invented by Benjamin Franklin in 1749 in the Americas, and independently by Prokop Divis in 1754 in Europe.

Historical understanding of lightning, from statements made by Ben Franklin, assumed that each lightning rod protected a cone of 45 degrees.This has been found to be unsatisfactory for protecting taller structures, as it is possible for lightning to strike the side of a building.