A Bolt Out of the Blue

 

QUESTION: I was browsing through an antiques mall when I spotted what looked like round glass globe lampshades. The dealer’s booth that contained them displayed at least a dozen. Some were opaque and others were clear glass and some had patterns. Unlike other 19th-century lamp globes that have a wider opening at the bottom and a narrower one at the top, the openings on these globes were the same narrow size on top and bottom. What sort of gas lamp were these used for?

ANSWER: Believe it or not, these globes aren’t for use on gas lamps but are part of a lightning rod installation. And unless you live in a rural area, you probably have never  noticed them on top of buildings.

Some lightning rod balls date to as early as 1840. Originally sold as ornaments for lightning rods,  today they can be found in a wide range of shapes and colors. Toward the end of the 19th century and beginning of the 20th, the use of lightning rod balls became common. 

In the 19th century, manufacturers embellished their lightning rod assemblies with ornamental glass balls. The main purpose of these balls, however, was to provide evidence of a lightning strike by shattering or falling off. If a property owner discovered a ball missing or broken after a storm, he or she would then check the building, rod, and grounding wire for damage.

A lightning rod is a lightning attractor or conductor. If it’s placed high on a building, it will draw the lightning towards it instead of other structures. The lightning rod comes in contact with an aluminum or copper plate on the roof. A grounding cable then runs inconspicuously across the roof, down the side of the structure, and into the ground.

There are around 34 shapes or styles of lightning rod balls. Traveling salesmen going from farm to farm in horse drawn wagons sold them from 1870 until the Great Depression closed businesses.

The most common lightning rod ball was 4½ inches in diameter and was smooth and round. The most common colors were opaque white, and opaque light blue. The next two most common colors were transparent cobalt blue and transparent red, sometimes known as "ruby" red. The holes in the top and bottom of the ball were the same size, and the hole and the area around it were called "collars."

Most balls had copper, aluminum, or sometimes    

brass "caps" on both ends. The purpose of the caps was to protect the ball and to cover up the rough glass edges created during its manufacturing process. Small metal rings, each with a set screw,  mounted on the lightning rod above and below the glass lightning rod ball to hold it in place..

In the 19th century, a farmer's barn was usually larger than his house. The lightning rod assembly was essential to protect these wooden structures from electrical storms. The glass lightning rod ball, placed at the center of the rod, was simply a decorative addition.

Sold by nearly every lightning protection company, the plain round ball was the moist common and came in three sizes—3½ , 4 and 4½  inches in diameter. Produced in milk glass, transparent glass and sometimes in porcelain, the standard ball was white or blue milk glass, and examples of these can still be found for $25-60. Both milk and transparent glass balls also came with a flashed coating—a process in which another color coated the original, such as blue over white, resulting in an opaque effect.

Transparent glass offered the widest range of color options, which ranged from clear to various shades of amber, cobalt blue, green, teal and red. Some clear balls now have an amethyst tint, the result of the sun's exposure to the manganese used in the glassmaking process. The deeper the shade of purple, the more desirable the ball is today.

Some manufacturers embossed their round balls with their name or further enhanced them adding quilted, pleated, or swirled patterns. While these can usually be attributed to specific manufacturers, they’re most often referred to by their shape, such as Chestnut„ Doorknob, Ear of Corn, Quilt Flat, Ribbed Grape, Onion, or Staircase. 

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