Of all the patents relating to insulators, probably the best known is No. 496,652 covering the addition of drip points to the base rim. This month is the one hundredth anniversary of that patent, issued to Ralph G. Hemingray and James C. Gill. Literally millions of Hemingray insulators were made with the embossing PATENT MAY 2 1893. They are in fact so common that even today, despite their age, they are of little value to collectors unless the insulator style or color is unusual. 

One might assume that a patent so well publicized was one of basic importance. Actually this is not the case. Water from rain will fall from the insulator rim quite as well without the points. The moisture from extremely high humidity and fog which does at times collect on the inner surfaces of the insulator skirt and cause considerable loss through current leakage is not affected by the presence of drip points. 

Yet, apparently many lines engineers, buyers and others were impressed. Even after the seventeen-year term of the patent (to the year 1910), the drip points appeared on most Hemingray styles well into the 1930s when they began to disappear from most newer styles as they were introduced. Their No. 42 had them until the last production during the early 1960s.

Even more interesting is the fact that several other manufacturers added points to their insulators after 1910. In some cases they were an option to be requested by the purchaser. In others, they were added to a majority of insulators produced. 

Western Electric, the largest buyer of insulators in the United States, seems to have tolerated rather than demanded drip points. Although a number of their specifications mention them as being acceptable on the product, none have been noted that require them.

The points are made by drilling a series of depressions in the portion of the mold that forms the base rim of the insulator. As the mandrel is unscrewed from the glass after molding, that portion of the mold is lifted along with it, freeing it from the points. The shape of the points was determined by the configuration of the bit used to make them. In some cases, the points would have been sharp but the glass did not quite fill the cavity so they appear as round drips. In some cases they are round on one side of the insulator and sharp on the other. This was not intended but resulted from a slight shortage of glass, or more rapid cooling in one area so the points were not quite completely formed. In later production where the points are quite uniform and perfect, there was likely special tooling in the mold shop for creating them.

If you are fortunate enough to live near an open wire line having insulators with drip points, here's a suggestion. On a rainy Sunday afternoon when you have become bored with TV, take your binoculars and drive to the line, park under a pole and look upward. You will see raindrops falling neatly one at a time from each point, just as outlined in the patent and just as they have done for the past 100 years. And if you believe in a life hereafter, you can visualize Ralph Hemingray and James Gill smiling down upon you, pleased that someone still appreciates their invention.

HIGH-TENSION POWER TRANSMISSION, SECOND VOL., 1904; article HIGH TENSION INSULATORS, by Vernon G. Converse

Mechanical requirements, such as strength, mounting, method of fastening the wire, color, etc., are in general, dependent upon the conditions to be met.

It does not seem as if details like gutters, spouts, drip points and the like can be considered of much value. They are features which may look well in theory, but can cut little figure in practice. Certainly the insulator of our high-voltage lines is more dependent upon good, strong insulator with liberal margins of safety, than upon such refinements.

BROOKFIELD GLASS COMPANY Catalogue, 1912

Many designs other than those listed and described in this catalogue are manufactured by THE BROOKFIELD GLASS COMPANY, and insulators with and without drip-points constantly are carried in stock. These will be found listed and described in the following pages. Unless otherwise specified, however, insulators without drip-points will be furnished.

AMERICAN TELEPHONE AND TELEGRAPH COMPANY Specification #4114, dated August 12, 1920 (for Exchange Insulators, CD #115)

FINISH: The finish of the insulators with respect to smoothness and evenness of surfaces and freedom from flaws, cracks, bubbles, sharp edges, and other defects shall not be inferior to that of samples approved as illustrating the limits for these features.

Insulators conforming in all other respects to the requirements of these specifications but having on the lower edge of the petticoat a series of projecting points may be accepted under these specifications. The insulators may carry on their top surface or on the outside curved surface near the bottom, a numeral to designate the mold used in their manufacture. They may also bear on the outside curved surface near the bottom, the manufacturer's name or trade mark and the number or listing employed to designate the insulator. Such designations shall be in raised characters smoothly molded in the glass; they shall be free from sharp edges or projections, and shall not extend more than three sixty-fourths (3/64) of an inch above the surface of the insulator.

LYNCHBURG GLASS CORPORATION price list dated April 1, 1924

Can furnish above with or without DRIP POINTS. Where not specified will furnish DRIPS. Above prices are for standard package quantity of each individual type of Insulator; a charge of $1.00 per package extra will be made for less than standard packages.

TERMS: Net 30 days, less 2% for cash in 10 days from date of Invoice.

DISCOUNT: A discount of 5% will be allowed on CAR LOAD orders, solid or assorted, made in one shipment to one consignee and destination.

ALL PRICES F.O.B. LYNCHBURG, VA.