Glass balls hit their height of popularity in the 1920s. At that time it was believed that they served a dual purpose – decoration and function. The glass balls were placed in finials or lightning rods for decoration. It was believed that if lightning were to hit the rod, the glass ball would shatter. If the ball were to shatter, the property owner would know to check the building for property damage.
It has now been shown that the glass balls will not shatter if the lightning rod is hit, but will rather pass through the glass on down the conductor to the ground. So, the one purpose left is pure decoration.
Glass balls or orbs for roof ornamentation come in many different sizes and colors, and to a small extent, shape. The color of the orb may be chosen to complement another color in the design, or to contrast and stand out. The balls are frequently installed into finials or weather vanes that often double as lightning rods. The glass orbs are an additional way to differentiate your house from others.
The glass balls are typically solid, so they are substantial and not easily shattered. They are placed in the weather vanes or finials that are traditionally made of copper or aluminum, although they may be made of other metals.
Placing a glass ball at the pinnacle of your house is a sure way to add a little of your own personality to your copper roof.