Hemingray-Brookfield Spiral-Groove Aqua-Green Vintage Glass Insulator
Aqua-Green Brookfield Spiral-Groove
Nicknamed the spiral groove because of the unique spiral-shaped wire groove patented on October 8, 1907. These were made both by Hemingray and Brookfield. The quickest way to identify a Hemingray-made CD 147 is to check the embossing. "PATENTED OCT 8 1907" will always appear together on one side of the insulator. (Brookfields always have a separate "PATENTED" on one side by itself.) Hemingray also manufactured the un-embossed CD 147.
Note: The insulators a free of any major cracks but might have some minor nicks/chips.
Use this insulator with my indoor lamp base.
Insulator diameter: 3.0 inches
Glass insulators were first produced in the 1850's for use with telegraph lines. As technology developed insulators were needed for telephone lines, electric power lines, and other applications. In the mid 1960's a few people began collecting these antique glass insulators. Today there are over 3,000 insulator collectors.
All glass pintype insulators are classified in what is called the “CD Numbering” system of identification. This system was created and used by N.R. “Woody” Woodward, an early pioneer, researcher and author in the field of collecting glass insulators. The CD (Consolidated Design) numbers basically identify insulators by their shape and profile, regardless of exact embossed markings, glass color, or base type.