N. R. "Woody" Woodward is the author of THE GLASS INSULATOR IN AMERICA, 1988 Report and developed the Consolidated Design Numbers identification system for glass insulators. 

The following questions come from Steve Kelly of Tempe, Arizona

QUESTION: Where were most of the CD263's found? Do most of them date back to the turn-of-the-century? Compared to others, why such a complex design?

CD 263, the double petticoat Columbia, was manufactured by three companies (Brookfield, Hemingray and Oakman) over a period of nearly 30 years. Patent #451,950 which refers to the holes for securing the tie wire was issued to Samuel Oakman May 12,1891. The style became popular for use on the heavy direct current cables used with street railways and inter-urbans. Because DC was generally employed in this service, very large cables were used to avoid excessive loss. Also, since these cables were often located where workmen might come in contact with them, they were covered with thick layers of insulation which further increased their diameter. Thus the large saddle groove on the CD 263, as well as CD 257 and other cable insulators. A drawing from a 1906 Central Electric Catalogue shows how the cable was secured to the Columbia insulator. Since the weight of the cable itself was considerable, a very strong tie was not needed.

Columbia Insulator

The two cities in which I have seen the most Columbias are Los Angeles and Chicago. However, they were doubtless used in many places. During the early part of the century every major city and many of the smaller ones had street railways and interurbans connecting them. Most of these were gone before the memory of most persons living today: but these cable insulators were once very common.

QUESTION: Do the Hemingray products that have patent dates prior to May 2, 1893 and no drips date prior to 1893, or did they continue to produce dripless glass after 1893?

The May 2, 1893 patent application was filed January 3, 1893. It is safe to assume that drip point insulators were not manufactured in quantity prior to 1893. However, while a majority of styles of Hemingray insulators were available with drip points after that date, many were made with a smooth base rim, probably due to customer preference. The millions of CD 145 H.G.CO. made for Western Union, as well as CD 147 after 1907, have smooth base rims; also the CD 121 made for AM. TEL. & TEL. CO. These are examples; there are others. However, it would be correct to assume that most DEC 19 1871 dated pieces with smooth base rims are pre-1893; but we cannot be sure of this in each and every case. The 1871 patent would have expired prior to 1893; yet we have examples where both dates appear on the same insulator, indicating that they were made in old molds with drips added. Thus, it is possible as well that some of the pieces with smooth base rims and the 1871 date were made after 1893.

QUESTION: Did Eastern manufacturers compete against each other during the turn-of-the-century in trying to produce and distribute only quality uniform glass in various shades of aqua? If so, would they ship their colored glass out west for less visibility?

No special importance was attached to the color of the insulators in the early days. Following World War I, Western Electric began to complain about the heavily colored pieces: and only in 1931, ten years later, did they make essentially clear glass a requirement. Since Western Electric and Western Union were the major buyers, their demands governed the nature of the product on the market. Hemingray was forced to change its sand source at that time in order to obtain a sufficiently high quality to adapt to the decolorizing process. Thus the "Hemingray blue" and dark aqua colors of the 1920s came to an abrupt end. Thereafter only amber pieces made for high voltage work were heavily colored. 

Back to the original question: it is very doubtful that shipments were ever directed to certain markets because of the color of the glass. Natural glass ranges between blue and green, intensity of color determined by trace minerals in the sand. Other colors were the result of either of two things: (1) the use of brown and green cullet, and (2) attempts to decolorize that resulted in yellow and purple due to agents used. Or if large quantities of previously decolonzed bottle glass was used, a similar color could appear in the insulators. Thus the "dirty clear" and smoky purple items. Again, though, all of this variation was considered of no consequence.