1980 >> February >> Threadless Corner  

"Threadless Corner"
by Ray Klingensmith

Reprinted from "INSULATORS - Crown Jewels of the Wire", February 1980, page 13

"Putting All Your Eggs In One Basket"

It's been nearly two years in the making, but in some way, the Egg article has finally hatched. After Shirley Patocka's informative article in the June, 1978, issue of Crown Jewels, covering the CD 700 and 700.1, I felt I would wait a little while for collectors to digest the info, and perhaps have time to dig up some material on the CD 701, the cousin to the CD 700 series. 

There are several different styles of the "egg" insulator with a regular pinhole (one which does not travel completely through, as with the CD 700). To start things off with this article, I feel it would be best to begin with what was probably the birth of the "egg", with a history of William Swain and The Magnetic Telegraph Company. The Magnetic, the pioneer of private lines in the U.S., was formed in May, 1845. The building of the line, which was to link New York with Philadelphia, began in the fall of 1845. Construction began in Philadelphia, and followed the wagon roads. Norristown, at a distance of fourteen miles, was reached by early November. Doylestown and Somerville were soon passed, and by January, 1846, Newark, New Jersey, was reached. Reaching New York City remained a problem for quite some time, as the early telegraphers had not yet devised a method of crossing the wide Hudson River with the line. Various methods were tried, most with little success, for a period of time.

It is interesting to note the contracts for the line construction specified "insulators of the glass bureau-knob pattern".

Although the line met with great difficulties, owing to its early "trial and error" methods (and, may I add, mostly error), it still managed to become a financial success. Later, it was joined with Washington, D.C. and various other important cities in the east. 


Magnetic Telegraph Company correspondence paper from 1853, showing
office locations and instructions for those sending messages.

Newspaper men were among those who used the telegraph, and contributed much to its success. One of these men was William M. Swain, proprietor of The Philadelphia Public Ledger. Swain was one of those who pledged money to The Magnetic in its early history. His overwhelming interest for the success of The Magnetic line eventually resulted in his becoming President of The Magnetic in 1850.


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Swain was a true businessman to the extreme. He was described by various people who were associated with him as a man of positive character, determination and hardness. James Reid, in The Telegraph in America, stated that Swain's favorite motto was "Business is business". After taking over the presidency, Swain made many changes in company policy which resulted in a large increase in business. The following is taken from The Telegraph in America, by Reid: 

As a telegraph officer, he at once gave vigor, method and responsibility to the business. His predecessor was far too delightful a man for such a position. The change of administration was felt at once when Swain took the reins. He first had the outward structure carefully inspected. Although a large man he personally accompanied the inspect ors of the line on foot over every inch of the route from New York to Washington! He reported having found 3,000 escapes and removed them all! He accepted nothing at second-hand. He had the whole line stiffened, straightened and cleared of obstructions. Not a leaf was allowed to touch the wires. Not a pole was allowed to lean. He then studied insulation, and made a sketch of what is known as the egg insulator. "That," he said, taking me into his office one day, " is the insulator of the future." He deemed good glass good enough, and the egg shape the form of maximum strength. 

That was the feature which he wanted. The line was quickly stripped of its former insulation and equipped with egg insulators, first on wooden brackets and afterward on iron pins. The long gaps of hours during which the service of the line had often been suspended by rains and crosses and escapes and broken wires, soon disappeared.

The insulator shown in Reid's book may have been drawn by Reid himself, and it is difficult to determine by looking at the drawing whether Swain invented an insulator with a then pinhole or a regular pinhole. That question has bothered me for quite some time. Some collectors have felt Swain's invention was in fact the "thru pinhole egg", but I now believe that style was simply a later variation. In The Telegraph In America, Reid states ".... equipped with egg insulators, first on wooden brackets and afterward on iron pins.", in referring to the first use of Swain's egg insulator on The Magnetic line, which is an indication the pinhole did not carry completely thru the insulator. The regular deep green eggs (style A) have been found in the east, where The Magnetic Tel. Co. was located. As near as I can determine, nearly all of the thru pinhole types have been found in the west, from lines which would have been constructed at a later date, perhaps the late 1850's and 1860's. Evidence of Swain's "egg" having been of a regular type is further shown in the following article written by F. L. Pope, appearing in the September 10, 1871, issue of The Telegrapher

About the year 1850 or '51 Wm. M. Swain, who was then President of the "Old Magnetic Line" between New York and Washington, designed the well known "egg insulator," shown in Fig. 2. Considering the imperfect state of electrical knowledge at that time, there is a wonderful amount of ingenuity and adaptation to circumstances displayed in this design. It not only stamps its author as a man of decided originality but also of sound practical common sense. It is very much to be regretted, on this account, that he did not remain in the telegraph business the rest of his life.

In designing the model of this insulator Mr. Swain succeeded in combining excellent insulating qualities with the highest degree of strength and durability. The general form of the egg or double cone is the strongest that could possibly have been selected. In fact, it has not been an uncommon occurrence for one of these insulators to be dropped from the top of a high pole upon a stone pavement without material injury. Under the ordinary conditions of exposure in the telegraphic service they are very rarely broken. 

In considering its insulating qualities, we find that the conducting surface constantly grows narrower from the wire at 1 to the support at 3 (see Fig. 2). During rain a portion of the falling water drips from the flange below the wire at the point 1, thus reducing the conduction from thence to the point 2. The insulating space between 2 and 3, although too short (and this is the principal defect in the design), is of great value in point of resistance, on account of its narrowness -- or, in other words, its small diameter -- which is rendered possible by the use of an iron support in place of the wooden pin previously used. This support was an iron L shaped arm, driven into the post. The whole formed a most substantial and durable mode of construction, which was actually better, both in design and execution, than that usually employed at the present day. 

The effect of the adoption of Mr. Swain's improvements in telegraphic construction upon the receipts of the Magnetic Company's lines was as follows: 

CASH RECEIPTS OF MAGNETIC TELEGRAPH CO.

For year ending July 1, 1848  $52,252. 81
For year ending July 1, 1849 $ 63,367. 62
For year ending July 1, 1850 $ 61,383. 98
For year ending July 1, 1851 $ 67,787. 12
For year ending July 1, 1852 $ 103,860. 81

Mr. Swain was elected President in 1850. It probably required about a year for him to get his improvements well under way, and the next year following (1852) shows an increase in the receipts of nearly fifty per cent! 

The egg insulator, upon an iron support, was also quite extensively used from 1851 to 1860 upon many of the telegraph lines in the Eastern and Middle States. 

Figure 3 is an insulator which was taken from an old Fire Alarm wire in Providence, R.I., and, as near as can he ascertained, originated in Boston. As will be seen upon inspection, it is an improvement upon Mr. Swain's model in one very important respect, viz., the narrowness and depth of the inner cavity. Its only drawback is an insufficiency of material, and therefore of strength at the top, above the upper end of the support. Like the Swain model it is designed to be fixed upon an iron arm. 

After the egg insulators had been in use several years the wires began to work very badly, and show a great deal of escape in wet weather. This was principally caused by the surface of the glass deteriorating from exposure, and becoming coated with dirt and smoke from locomotives and other sources. 

The true cause, however, was not at that time understood or even suspected. The managers of telegraph lines "jumped" to a conclusion, which, as usual, was an erroneous one -- that the trouble was owing to the egg insulator being too small at the bottom. A certain distinguished advocate of glass insulation remarked: "When I find that a parasol is a better thing than an umbrella in a big rain, then I shall begin to believe that the egg glass insulates better than the umbrella." The iron supports also came in for a large share of the general condemnation. 

So all the "egg glasses" and iron arms were thrown away, and a new era of experimenting commenced. Many lines adopted the hard rubber insulator, and others the Lefferts plug. The advocates of glass returned to the old "umbrella" (Fig. 1), which they mounted on wooden pins, under the mistaken idea that these helped the insulation. This was true to a certain extent, but, on the other hand, the larger opening beneath the insulator, rendered necessary by the greater diameter of the wooden support, much more than made up the difference. 

Another popular fallacy, that prevailed extensively about this time, was that the larger the insulator, and the more glass there was in it, the better it would insulate! This absurd idea, which, it is almost needless to say, was directly the reverse of the truth, was carried out on a large scale on many lines that might be mentioned. The result, of course, was far from satisfactory.

Pope's article gives much information as to the use and development of the egg. The insulator shown in his Fig. 2 is identical in shape to the insulators (style A) found in the east in a very deep green color. They are the same in every detail, including the base which has a slight indentation and a raised ring. The improved insulator (Fig. 3) shows an egg with a larger skirt interior (style B). Pope states he believes it to have originated in Boston. It is interesting to note that eggs of that type have been found throughout the New England area. Before going into detail on the color and style variations of the eggs, I thought I would cover the development of the insulator. The following pages, taken from an 1859 book, certainly give a great deal of info on the various applications of this insulator. It is very interesting to note the "threaded" egg in the material. Remember, this was in 1859, and prior to Cauvet's 1865 patent. 

This insulator was again improved by Mr. William M. Swain, president of the Magnetic Telegraph Company. He abolished the flange and constructed the glass in the shape of an egg, as represented by the following figures. 

Fig. 20 represents the form of the glass with line wire groove at its centre. The lower end is concave and the upper slightly convex. The flange insulator was easily broken, but the egg form cannot be broken by the ordinary service of the telegraph. I have seen this insulator thrown as much as a hundred yards, and against brick houses, and not break. This rotund-shaped glass insures long service, as has been demonstrated by its use on a long range of lines for many years.

In the arrangement of this insulator Mr. Swain did not only have in view substantiality, but also the perfection of the insulation of the line wire from earth currents. At number 1, fig. 21, the cone is concave. when the water collects upon the upper part of the insulator it does not follow the glass to the numeral 1, but falls from the centre projection. The moisture under the drip forms globules, and breaks from the cone at or above 1, as seen falling from the flange of the cone, fig. 25. The point of drip, therefore, is not at the lower end, but above at the centre projection as just described. Fig. 26 represents the drip of a house. 

The falling drop breaks the rain and keeps dry the projection seen under the eave of the house. In the same manner the dripping from the above described glass insulates the lower cone from the rain.

Of course the lower end of the glass will not be dry, but there will be less liability for a watery connections with the earth from the wire than when the drip is at the lower end of the glass. I have seen this philosophy illustrated at the Niagara Falls. The immense volume of water passes over the shelf or point of drip, and beneath the mass of water is a passage-way for travelers, precisely as represented by fig. 26. If the reader desires to see this idea illustrated, he can do so by setting a teacup upon an upright pin, then fill the cup with water until it overflows. The water will fall over the rim, and the smaller end of the cup will be dry. 

Fig. 21 represents the glass adjusted to the wire when on a right line; fig. 22 when the wire is oblique, as upon the side of a hill, and fig. 23 when the wire is perpendicular with the post. In order to prevent the glass from pulling off from the iron arm, the screw combination represented by fig. 24 was adopted. The iron arm 3, is cut so that the teeth will serve as a male screw. The glass is made with a female screw as seen by numeral 2. Fig. 25 represents the glass on the arm, with the line wire fastened to it at an angle pulling the glass upward, the teeth of the iron arm fitted into the grooves of the screw prevents the glass from being separated from the iron arm.

The above figures are engraved with so much variety that further explanation is unnecessary. They have been gotten up with care, and they are replete with demonstrative philosophy. 



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On the previous page is a copy of a patent issued to Amasa Stone of Philadelphia, Pennsylvania, on Aug. 7, 1855. The patent material mentions it was a method of forming screw threads not only in bottles but also insulators. In fact, insulators are mentioned throughout the patent application. Amasa Stone is listed as a fruit jar manufacturer from 1857 to 1861, and in the years 1862 and 1863 as a patent glassware manufacturer. Fruit jars with the internal threads and matching screw threaded cap are known to jar collectors. Various sizes of A. Stone jars with the threading have been found. There also is a rare jar embossed with the name "The Great Eastern", with a similar threading. The Great Eastern was the ship which laid the Atlantic Cable in the mid 1860's. This "jarring" information may seem unimportant, but it indicates Stone was involved with the actual manufacture of jars made under his patent. 

At this time no egg insulators have been found with the screw thread, but it seems very likely they were produced. First, they are listed in the 1859 book as being adopted to prevent the glass from pulling off the iron arm, which indicates the author of the book probably saw the actual insulator, or was very up to date on patent information. Second, Amasa Stone was involved with the production of jars with the screw thread, so it seems likely he also could have produced the insulator. Third, it is interesting that Stone chose the egg style for the patent drawing. Remember, Swain, inventor of the egg, and President of The Magnetic until 1858, was proprietor of a Philadelphia newspaper, Philadelphia also being Stone's hometown. It seems very likely Stone and Swain could have known each other and produced the threaded egg.

The Magnetic Telegraph Company existed until 1859, when it was consolidated into The American Telegraph Company. The threaded egg could have been used on a Magnetic line prior to the consolidation, or perhaps later on on an American Telegraph Company line. 

In a phone conversation with Wendall Hunter, who initially brought my attention to the Stone patent, Wendall mentioned there was also a wealthy Amasa Stone of Cleveland, Ohio. Wendall stated he believed reading the A. Stone of Cleveland was on the Board of Directors of the Western Union Telegraph Company, possibly in the 1860's. This could be the same Amasa Stone that was earlier in Philadelphia. At the present, I have no proof they are the same person, but most likely they were. If they were, it shows Stone's interest in the telegraph, first in a patent showing an insulator, later producing a jar named after the ship that laid the Atlantic Cable, and still later, on the board of a telegraph company. So, there are probably threaded eggs out there somewhere! 

Now, finally getting to the insulator variations. Most likely the first egg insulators used on the Magnetic line were of the type shown in Fig. 4 (style A). These have been found in the east and south. They most likely were used on The Atlantic & Ohio Telegraph Company line, as one of these was found in a small Pennsylvania town where that line went through. They were used in New York State on a line which reportedly gave a lease to the Magnetic, and they have been found in the southern states. 

Amos Kendall, the first president of the Magnetic, labored to connect the Magnetic line in Washington, D.C. with New Orleans. The Washington & New Orleans Telegraph Company was formed in 1846 and may be the source of many of the eggs which have been found in the south. The line connected Petersburg, Lynchburg, Suffolk and Norfolk, Va., Raleigh, N.C., Augusta, Savannah, Midville, Atlanta, Macon and Columbus Ga., Montgomery and Mobile, Ala., and New Orleans. Style A may have also been produced during the Civil War for the Confederate Army lines. The pinhole interior of the ones used on the New York State line are marked with many irregular recessed lines as shown in Fig. 4. This appears to have been done when they were manufactured, to allow the pin and insulator to be cemented together, having a better hold, due to the cement filling the small recessed lines. I'm not aware of this method having been used elsewhere. Style A has been found in deep olive green and a deep green with a teal tint. The manufacturer of these is unknown at present. I've always thought perhaps the dark coloring of these and other threadless were made that way intentionally. Perhaps the reason was the fact that a dark colored object will absorb heat more readily than a light colored one, and thus evaporate condensed water from the surface of the insulator at a faster rate, giving better insulation. 


Fig. 4. Style A. Note pinhole begins near base, and base with indentation and ring, which is prominent on some, nearly non existent on others. 
Size is 3-7/8 x 2-1/16.

Fig. 5. Style B.
Note pinhole is higher in the insu lator body, and rounded base. This  is the "improved egg. 
Size is 4 x 2-1/8.

Fig. 6. Style C.
Note indented sides of dome.
Smaller than styles A and B.
Very light green, almost clear.

Fig. 7. Style D.
The "National Road Egg". The smallest of the glass eggs, measuring 3-1/2 x 2-5/16.


Dick Bowman photo 
Fig. 8 From left to right: a very bubbly aqua style B, 7up green style B, 
lite yellow-green style B, deep teal green style D, 
the "Confederate egg" style F. 


Fig. 9. Style F. 
The "Confederate egg". Note extended base and recessed dome top. Size is a huge 4-3/4 x 2-7/8.

Fig. 10. 
The grey porcelain egg, reported to have been made in Richmond, Va., ca. 1861.

Figure 5 shows style B, which F. L. Pope mentioned in the material written for The Telegrapher, which was shown earlier in this article. Pope stated "....and as near as can be ascertained, originated in Boston", referring to style B. I'm not certain if he means that style originated in Boston, or if the glass was manufactured in Boston. Most likely style B was produced in the Boston area, as a number have been located throughout Massachusetts and various New England states. In fact, I'm not aware of any being found outside the New England area. They have been found in aqua, bubbly aqua, seven-up green (possibly two different shades), lite yellow-green, lime green, clear with a grey-sca tint, clear with milky streaks, and there is rumor of one in cobalt blue! The glass in the clear and lighter colored ones appears to be of high quality, similar to that used in stemware and other household glassware.

Doug MacGillvary reported a near clear egg was dug at the site of the Coventry Glass Company in Connecticut. However, further research by Doug revealed Coventry went out of business in the 1840's, prior to the production of the eggs. Perhaps it was used on a nearby telegraph line, or maybe there was a later glass company at the site which we don't know about. 

There also was a clear or near clear egg dug at the Sandwich Glass Company dumpsite. (Correct name may be Boston & Sandwich Glass Co. I didn't do my homework.) I was told it had an indentation on the dome which may have been an imperfection, or perhaps it was like figure 6, style C, which may have been a different type of mold than style B. At any rate, Sandwich produced clear and colored glass. They were in business in the 1850's and into the 1870's, if my memory is correct from the visit I made to the Sandwich Museum four years ago. Once again, however, there was a telegraph line through the area which may have been the source of the insulator. However, due to the fact that Sandwich produced a high quality, clear and light colored glass, among other colors, I feel that the one found at the site, and perhaps a large part of those found in New England, were produced at Sandwich. There were a large number of glasshouses throughout New England, and it's possible several companies produced insulators. 

Figure 6, style C, is the same as style B with the exception of the indented dome. This may have been a manufacturing deformity, but I personally feel it was intentionally made that way in a different mold than style B, so am classifying it as a different style. Color is a very lite green, almost clear. 

Figure 7, style D, is a somewhat smaller version than the rest. It has a pinhole somewhat similar to the revised model (style B), but has the indentation and extending ring on the base, similar to the base on style A. As near as I can tell, all of these originated in Ohio, and all may be from a telegraph line which followed the National Road. There have been threadless insulators found beside and in the area of the National Road over the years, and it's my belief all the style D eggs were used on that line. The National Road was an early wagon road which traveled east and west through Maryland, Pennsylvania, West Virginia, Ohio, Indiana and Illinois. It eventually linked St. Louis with Washington, D.C. and Baltimore. Thousands of people used the road in the middle 1800's, and it was the primary wagon road of the large area in its day. Of the three style D eggs I've seen, two were aqua, and one was a more sparkling darker shade of blue-aqua. The darker blue-aqua one was uncovered by a bulldozer doing some excavation for a modern road which replaced the old National Road. 

Style E is a larger egg which has been found in the south. It is similar to the deep green Magnetic type, but is taller and wider. (See fig. 8, second from right.) In viewing the regular sized egg and this larger one "in person", a big difference in their size can be seen. I believe one of these was found in Virginia and one in Tennessee. This style has also been found in Mobile Bay, Louisiana. This item is found in the deep green with a teal tint, and I believe it also is known in the regular deep green. This item is uniform and neatly made. 

Style F (figures 8, 9 and 13) is a real crude monster measuring 4-3/4" tall by 2-7/8" wide at the base. This insulator in my opinion is the most crudely made of all insulators. It looks like a piece of dark green wax which a three year old child has just carved with a knife in the shape of an insulator! This insulator is very near in shape to style E, except that this one has a long extended base and is crudely made. The surface on this large insulator is very coarse and pebbly. The wire groove at some pints is nearly filled with glass, and the dome top is recessed into the insulator. (The dome top is formed in a saucer of bowl-like depression -- see Fig. 9.) The base on these flares out forming a concave skirt and has an extension which projects downward 1/2 inch. The extension is on all of the style F units I've seen, and I would guess they were intentionally made that way. These are nicknamed "The Confederate Egg" because of their being found in areas once occupied by Confederate troops during the Civil War. This insulator was found in Mobile Bay where the Confederate Army reportedly built a telegraph line on a bridge across the bay. (Also found with these were styles A and E.) One also was found along a railroad right of way near Richmond, Va. 

I sometimes wonder if perhaps the mold used to produce style E was badly damaged in some way, perhaps by overheating, or exposure to water, which resulted in a rough surface on the mold interior. Assuming these were made during the Civil War, for Confederate use, the main factor concerned would be good insulation, and not a nicely made insulator. So, in my opinion, the style E mold could have been damaged and altered, and the style F egg then produced in the same mold. It's also quite possible that with a lack of proper equipment to make a fine mold, during the Civil War, a Southern manufacturer made one as best it could, using a style E egg for a model. One must remember that supplies in the south at that time were very limited, due to the fact that the major industrial areas capable of producing equipment were in the north. Before going on to the next item, I thought I'd point out the fact that the style F egg has a large pinhole which tapers from 1-1/4 inch at the bottom to one inch at the top. 

Next on the list of eggs is the porcelain, which measures 3" x 2-5/8". These have been assigned U970 in Jack Tod's Universal Style Chart for porcelain. I know of five of these in collections. One of these was found at the site of an encampment of the Alabama Department of the Confederacy near Dunfries, Va. Between twenty and thirty were found at the bottom of the old Kanawha Canal several years ago by someone who didn't know they had any value, and unfortunately left them there. Sorry to say, they are now buried under tons of dirt. These are reported to have been made in Richmond, Va. at Parr's Pottery in 1861. There are two reports on their use -- one on a telegraph line parallel to the railroad between Richmond and Fredericksburg, and the other on a line between Richmond and Yorktown. Of the five I know of, three have a lite cream-tan glaze, and one a grey glaze. Dick Bowman reported his has a nail through the body of the insulator! Dick stated the nail is rusted, and it appears as though a hole was made in the skirt area prior to the firing of the porcelain, and perhaps when placed on a pin, the nail was inserted. If you can't cement a threadless to a pin, why not nail it on! One of the other porcelain eggs I saw had a repaired area on the dome and appeared as though an attempt was made to drive a nail hole, and in the field a line constructor got the idea of driving the nails into them; but, as stated, Dick indicated the hole in his appeared to have been made prior to firing it. All this is very interesting, and I wonder how the nail driven into the pin may have affected insulation! 

At present there are seven distinctively different styles of eggs. It appears these were in use from 1850 or 1851 and probably until or shortly after 1870. I had believed they were probably no longer produced after the Civil War, but the ad shown above indicates otherwise. I believe this was from the March 1868 issue of The Telegrapher. Bartlett was offering "Eggs" at that time, and one could assume they are referring to that type covered in this article. I'm not sure if Bartlett was in Boston or New York. I would assume it to be New York, as that is where The Telegrapher was printed, and the ad doesn't indicate another city. Bartlett probably was from there also. 


Fig. 11 
The "thru pinhole type" eggs. From The Glass Insulator-- A Comprehensive Reference by Cranfill & Kareofelas.

Fig. 12. 
Various iron brackets used on an "egg line" in New York, shown with style A insulator used on that line, and style F used in the South.

Fig. 13 Style F. 
The big crude monster.

Paul Plunkett photo 
Fig. 14. The seven up green style B.

Paul Plunkett photo 
Fig. 15. 
A bubbly aqua style B.

Fig. 16. 
The lime green style B. High quality glass similar to that for household use.

The brackets shown in figure 12 are all from the New York State line described in the information on style A. They are hand forged iron. The longest one in the photo measures 14-1/2 inches. Unfortunately for collectors, when the insulators and brackets were removed from the poles, it appears as though a hammer or large object was used to smash them off the pole, breaking all the insulators. 

If anyone has any additional information or color/style variations not listed, please contact me (Ray Klingensmith, 709 Rt. 322, East Orwell, OH 44034), so that is can be placed in an upcoming "Threadless Corner". A big thanks to the following people for photos, information, written material, and also for allowing me to photograph items in their collections, etc.: Dick Bowman, The Branhams, Gary Cranfill, Dennis Donovan, Glenn Drummond, Fred Griffin, Wenall Hunter, Mike Johnson, Frank Jones, Greg Kareofelas, Doug MacGillvary, Mike Sovereign, and the Paul Plunkett family.



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