The growth and development of the telegraph industry was pushed forward with an energy within its promoters unsurpassed by men of other trades. Visions of a vast network of wires, connecting every important town and city on the continent, filled the minds of many. With this energy came a creativeness in the invention of insulators. For every line built there seemed to be three new ideas for insulating the wires. This creativity seemed never-ending, and as more lines continued to be built, an even greater variety of insulators made their appearance.
This inventive creativity continued for decades and the result was thousands of varieties of insulators. Despite all the special designs, all the patented features, the variety of materials and arrangements devised in an attempt to make the "ultimate" insulator, the fact remains that a design developed by George Little in 1846 continues as a style not much changed and still in use today. James D. Reid, the telegraph historian, states:
In this field an English inventor, now a resident of Virginia, named George Little, better known in connection with automatic telegraphy, produced in England, in 1846, one of the more valuable of practical and readily applied forms. The Little English insulator was of glass with umbrella or saucer base. Glass insulators in the form of bureau knobs were in that year in use in America. In 1847, with the rapid substitution of iron wire for copper, insulators of the Little form were employed. They were credited, probably with justice, to Ezra Cornell. Innumerable forms with this as a basis have since then been common, and almost universal.
Reid's mention of Cornell is in reference to his adopting the Little style and promoting its use in America. The Little insulator was the type we now refer to as the
pilgrim hat
style. These were produced with either one wire ridge or two. T.P. Shaffner in The Telegraph Manual, printed in 1859, illustrates three hat styles and gives the following explanation:
Figure 6. Figure 7. Figure 8.
In the adoption of the glass insulator the form first employed was the ordinary door-knob. It was found to be a partial success, but the large projection at the top of the knob was considered useless, and then the shape represented by Figure 6. was employed. The glass was set on a wooden pin fixed in a cross beam at the top of the pole. This form was then improved as shown by Figure 7. The wire was laid in the grooves of Figure 7. and on the projection in Figure 8. The line wire was then tied to the glass with a small wire, either No. 16, No. 14 or 12, according to circumstances and the opinion of the constructor. (p. )
While it is difficult at the present time to establish an exact date when each of the varieties of pilgrim hat or Little style insulators was produced, it is safe to assume that CD's 735.6, 735.7, 736, 737, 738 and 739 were most likely initially manufactured in the late 1840's to early 1850's. The type represented in the illustration (Figure 8.) was in use on Morse's Washington-New York line in 1853. The CD 735.6 and CD 739 have been found along the right-of-way of the New York & Erie Railroad, on a section of telegraph line built in 1850. While they could have been placed in use there at a later date, it is likely these types were being produced at that time.
The CD 736 was used as early as 1851, as near as can be determined. In May of that year, the New York & Erie Railroad was completed from the Hudson River to Lake Erie with a telegraph wire for railroad use along the right-of-way. Both the CD 736 and CD 736.1 styles saw extensive use along the main line and branches of the Erie Railway which came into existence in 1861 with the demise of the NY&ERR.
Some of the larger pilgrim hat styles in the CD 735.6 through CD 739.2 series, which are among the oldest of pintype insulators, saw production into the late 1860's and possibly into the early 1870's. They were a popular design with some of the telegraph men of the time.
With the extension of lines into remote areas, it became advantageous to reduce in size this style of insulator to help in reducing weight and bulk in transporting materials. The result was the CD 735. The earliest confirmed use of that insulator style was on the Collins Overland Telegraph Company line being constructed in 1865-1866. The first shipment of insulators arrived in British Columbia in June 1865, after having been shipped from New York in late 1864.
They were also widely used on the route of the Union Pacific Railroad being constructed in 1868 and 1869. Other similar styles including the CD 734 McMicking and CD 734.5 "Baby Battleford" were produced as late as the middle 1870's. The large number of variations in the CD 734 through CD 739.5 grouping were produced by several glasshouses, but only a few can be accurately attributed.
Another group of the hat style insulators is the CD 740 through CD 742.3 group. While they are similar in some ways to the previously-described pilgrim hat styles, they differ primarily by having a more squatty form and in most cases a more rounded dome. While an exact date has not been determined for their earliest manufacture, it would stand to reason their production was started no later than the early 1850's, and perhaps the late 1840's.
The Canadian lines saw a widespread use of insulators in this category. Examples of CD 740, 740.2, 740.3, 740.7, 742, and 742.3 were used and most likely produced there. Literally millions of the various styles mentioned above were in use by the 1870's. The Montreal Telegraph Company, formed in 1847, monopolized the telegraph industry at the time and spread its lines to nearly every major town in the provinces of Ontario and Quebec, and later the Maritime provinces. It is likely their early lines were constructed with the CD 718 and 740, but in later years the CD 742 and 742.3 styles saw widespread use.
In the U.S., the unembossed CD 740 was used primarily in New York and the New England states, although they have been found in other areas. They were most likely produced at several different glasshouses over a period of years. Most of them are of dark coloration, usually green or amber. While the CD 740.1 is of Canadian origin, a few have surfaced in New England, primarily on the Grand Trunk Railway line which entered Vermont from Quebec and terminated in Portland, Maine. This style, from the evidence available at this time, appears to have been used exclusively by the Grand Trunk Railway in Canada and on the above-mentioned line into the U.S.
Of the remaining variants in the grouping, the CD 740.4 has been found primarily in New York state. The embossed examples will be discussed in the chapter covering telegraph supply houses.