A Chapter About Insulators

Reprinted from "INSULATORS - Crown Jewels of the Wire", December 1982, page 10

In no department of telegraphic science has so much ingenuity been expended, and so little real progress been made, as in that which relates to the proper insulation of the "line wires." Many of these devices -- "and their name is legion" -- possess a high degree of merit; but let a heavy fog or rain prevail for a few hours in succession, and the vexed and wearied operator is forced to admit that we have advanced but little, if any, in this matter, for the last ten or twelve years.

It is true, there has been manifest improvement in some respects. The lines are more carefully constructed and located than they formerly were, as regards their liability to come in contact with trees, buildings, and other obstructions, and a more diligent use is made of what a telegraphic friend was wont to term "the best of all insulators," a good, sharp hatchet. 

Most of the insulators now in use throughout the United States, are of the following varieties: First, the time-honored, and well-tried glass insulator, either of the "egg" or "bell" pattern, mounted upon a wooden or iron bracket. Second, the "Wade," alias the "nigger head" insulator, of glass, with a wooden shield, or protector, and placed upon a wooden bracket. Third, the "American," or "Leffert's" insulator, which holds the wire suspended in an iron hook, cast in a glass socket, which is inserted into the under side of an arm or block of wood, secured to the side of the pole.

The unprotected glass insulator, first mentioned, is more or less used by every Telegraph Company in the Union, more extensively, probably, by the "United States" and "Independent" than by any other lines. At the present day, a wooden bracket or pin is almost universally used, as its support upon the poles, experience having shown that iron brackets were, in many respects, objectionable. Viewed solely with regard to its insulating qualities, it is, when properly constructed and arranged fully equal to any that has ever been used; but a fatal objection to its use in many parts of the country, is the repressible tendency of mischievous Young America to consider it a tempting target for a trial of his skill in the projection of stones, pistol shots, and other missiles. As might be expected, the lines soon present a dilapidated appearance, especially in the neighborhood of school-houses, and other exposed places, and the transmission of messages during the next rainstorm, is often accompanied by the maledictions "both loud and deep," of the much-enduring operators. Possible this might be remedied by using short poles, and placing the wires and insulators so near the ground that the said urchin would consider it beneath his dignity to throw at a mark "that anybody could hit." Any Telegraph Company wishing to try this experiment in human nature and telegraphy, is entirely welcome to the above suggestion.

The Wade insulator is largely used by the Western Union Telegraph Company. The wooden portion covering the glass renders it, in a great measure, free from the above objection, but gives rise to another serious one, which is, that when a breakage of the glass does occur, it is very difficult to discover it without making a minute examination of the line, while a casual glance, even from a passing railroad train, will at once discover a failure in the ordinary insulator. 

The "Lefferts" or "American" insulator, is now almost universally used upon the lines of the American Telegraph Company, and gives good satisfaction. When well made, it is not very liable to fracture, and as regards insulating qualities, it stands among the first. It is, to some extent, open to the same objection as the Wade insulator, mentioned above, but in case of a fracture, generally allows the wire, as well as the hook which supports it, to drop down, and thus discovers the fault.

The hard rubber insulator, in several different forms, was most extensively introduced throughout the Northern and Eastern States, but a few years ago, by the late Jas. Eddy, Esq. Probably not less than twelve or fifteen thousand of the well-known "rubber block" insulators were put up between the years 1855 and 1880, upon various lines. This arrangement consisted of a suspension hook for the wire around the shanks of which an insulator socket of hard rubber was moulded. A thread was cut in this, and it was screwed into a square block of pine, which was nailed to the side of the pole. Its convenient form and good insulating qualities rendered the "rubber block" very popular for a few years, but it is now generally considered to be a failure. The rubber socket splits after a few years exposure to the weather, which of course creates an escape during a damp state of the atmosphere. Some of the manufacturers contend, that this is not the case when the proper quality of rubber is made use of in the construction of the insulators; but experience will probably show that no organic substance can be relied on to withstand an exposure to the vicissitudes of a changeable climate, for an indefinite length of time.

An insulator composed of white flint similar in form to the ordinary one of glass, and known as the "Elliott," was used to some extent for a few years. From an experience of a year or two on a line which used them, I am inclined to consider them an excellent insulator. They are with difficulty broken, being very strong, and during moist weather, the dampness, apparently, has less disposition to condense itself into a conducting film upon this substance than upon ordinary glass. Further experiments should be made with this material, as the condensation of moisture is one of the principal objections to the use of glass as an insulator.

Iron Insulators are now mostly "among the things of the past." The fracture of the glass by the expansion and contraction of the iron casing surrounding it, and the difficulty of detecting these fractures when they occur, as well as the enhanced danger from lightning which the poles were exposed to, were among the principal objections to this form of insulator. One form is much used on the fire-alarm wires, in Boston, Providence and other cities, and is said to do good service.

This subject is a comprehensive one, and is also of vital importance to the advancement of our art. I have only aimed to call the attention of the readers of The Telegraph to it. Let some of our practical men give us their views, as well as a record of their experience in this matter, from time to time, through the columns of The Telegrapher. There is a wide field still open for improvement in this direction. I firmly believe that the day will yet come when our wires can be worked with rapidity and certainty at all times, regardless of the storms and fogs that are now equally dreaded by the employees and the patrons of the Telegraph. 

The foregoing article was reproduced from an old issue of "The Telegrapher" and was sent to us by Ted Griffin.