GEORGE W. KIDWELL INSULATOR 
Patent No. 120,884 dated Nov. 14, 1871

A new two-part glass telegraph insulator has been found! It was discovered by the American Resources Group, Ltd. in Salem, Illinois while performing archaeological work for the Illinois State Museum. As you can see in the photographs, the glass insulator is not a pin-type, but rather a cylindrical insulator.

The insulator was found at an excavation site near an old tavern on the St. Louis-Vincennes Trace paralleling the Ohio and Mississippi railroad. This broad-gauge railroad was completed in 1855 between Illinoistown and Vincennes. It is now part of the Baltimore & Ohio System. In 1857, the entire line from St. Louis to Cincinnati was completed. The cylindrical glass telegraph insulator was found about one foot below the surface in the remains of a shallow privy used by travelers at the local tavern. Other artifacts were found in the privy such as broken earthenware, glass bottles and flasks, a fork, and several buttons. This shallow privy was typical in that area near public buildings. The shallow depth allowed chickens easy access to undigested items in the waste.

Now for a description of the insulator: The glass is a light aqua color measuring 2-1/2 inches, long with a diameter of 1-5/8 inches. There is a central channel or groove 3/4 inches in diameter. There is an additional groove on the exterior surface that runs perpendicular to the length. This groove is approximately 7/16 inches in diameter. One end of the insulator has a flat surface and the other end a concave surface slightly tapering inward toward the wire groove (central channel). 

The insulator was manufactured based on the utility improvement claims of patent number 120,884 granted to George W. Kidwell on November 14, 1871. As you can see from the patent drawing, this insulator was originally intended to consist of two parts of equal size, together making a complete cylinder. It is common for actual production to vary considerably from the patent. This could be due to manufacturing problems or simply a better, more practical application by changing the patent design slightly.

The specimen is not one-half of a cylinder, but rather about 2/3 of a cylinder. This may have allowed easier placement of the telegraph wire in the larger part and easier insertion of the second smaller (1/3 of a cylinder) part. Also, it could have allowed the lineman to easily recognize which part had the perpendicular groove [the smaller part obviously did not have this groove]. This perpendicular groove received a wooden dowel permitting the insulator to be secured in the wooden block.

One claim in the patent was a semicircular projection with matching groove near one end that would not allow the two parts to slip apart. This specimen did not have this feature. With such a matching projection and groove, the two parts would be put together around the wire, then inserted into the wooden block. However, this would not allow the lineman to align the perpendicular groove with the wooden dowel. If this feature was not used, then the lineman could first insert the larger part into the wooden block, align this part with the wooden dowel, then insert the wire into the larger part, and lastly, insert the smaller part. The big drawback to this design is that the smaller glass part would eventually slip out and fall to the ground. The telegraph wire would be unsecured inside the hole in the wooden block, and, eventually, the larger glass part would fall out, too.

I wonder how this glass insulator found its way into a shallow privy? Have any of you seen this Kidwell insulator? Perhaps one of you has a "piece of glass" similar to this specimen laying around, but, until now, you were unaware that it was in fact an insulator. Or, perhaps you have found the missing 1/3!? How about some of you insulator diggers in the mid-west? 

I want to thank Dennis Weber for forwarding the request from American Resources Group (ARG). A very special thanks to Jane Johnston who is a staff archaeologist with ARG. She furnished photographs and a history, information about the location and details of the excavation, and generously arranged with the Illinois State Museum for me to borrow the insulator in time to take it to the Portland National.

If any of you have a patent question, please do not hesitate to ask. I now have copies of 1049 insulator patents and 36 design patents. Copies for any of these patents are available from me for $1.00 each.

Elton Gish, P.O. Box 1317, Buna, Texas 77612 (409) 994-5662