Anyone studying the past history of Canada runs into the name of Frederick Withycombe. In 1899 he patented the idea of making insulators with ridges all over them. This was not necessarily a new idea. The American inventor, Foree Bain, had patented a ridged insulator some nine years earlier, but for whatever reason the earlier product never caught on.

(Drawing is by Clay Salzman)

Two factors seemed to motivate the creation of ridged insulators: First, the ridges increased the surface distance between the wire and the pin, affording better insulation. Unfortunately, ridges are also dust-catchers, which then greatly reduced their insulating qualities. Second, it was felt that a ridged insulator would resist damage; that is, a rock or pebble might chip a ridge or two, but would not crack or destroy the insulator. In this latter regard the ridges seem to have been very successful in cushioning the rest of the insulator and reducing the severity of damage. 

Withycombes, as Canadian ridged insulators are called, are generally quite desirable, and some of them are extremely scarce. They are found in CD 121, CD 143 and CD 144. The 121 is fairly easy to find, and is the only one in which vertical ridges are continued at the bottom, so as to form wedge-shaped drip points. The CD 144 Withycombe is very scarce and very desirable. (It is sometimes called the "high groove" Withycombe.) All of the other Withys were 143's, and most seem to have been used on a limited-production or experimental basis. The only ones that appear to have been produced and used on a larger scale are the ones with only vertical ridges, and the Canadian Pacific Withy which was discussed in article #3.

In my 143 listings I have grouped all of the no-name Withycombes into mold style #7, although there are really three major styles, as well as additional sub-styles. By the way, the book lists a 143 Withycombe with an embossed patent date (like the CD 121 Withy). I have never seen this variety, and I doubt that it exists. 

The ridges on mold style #7A are all horizontal. There are 14 circular ridges above the wire groove, and 10 spiral ridges below. The lower ridges spiral down, left to right. The wire groove is large and is 1-9/16" from the base. The base is smooth and slopes in. I have heard that various colors exist, but I doubt some of them. Every one I have ever seen has been the same light yellow-green. 

Mold style 7B is a lot like 7A, with a few key differences: The wire groove is lower, and the spiral ridges below the wire groove go in the opposite direction! 7B has 16 circular ridges above the wire groove, and 8 spiral ridges below, which spiral down right to left. The wire groove is 1-1/2" from the base, and this variety comes only in the gray and SCA shades. Don't ask me why, but I have never seen a 7B in yellow-green, or a 7A in SCA. By the way, 7B's and 7C's seem to have come exclusively from the eastern provinces of Canada, while all of the 7A's were found in the West.

Mold style #7C is exactly the same as 7B, except that there are 19 circular ridges above the wire groove. 

Mold style #7D is a new discovery that appears to be slightly more modern than the styles listed above. It was made in a two-piece mold, but the overall shape is more like the vertical-grooved Withy (like mold style 7E, which will be discussed in a moment), although there are some key differences. The wire groove is approximately 1-5/16" above the base, but this measurement will vary, because the base is split by the mold: The inner half of the base is formed by the part of the mold that includes the pin hole, and the outer half of the base is made by the part of the mold that makes the exterior sides! 

I have never seen a base like this before. If there is an excess of glass in the pour, then the inner half of the base protrudes. If there is a short pour, then the inner half of the base would be recessed. So variations in the amount of glass poured will affect the height of the insulator.

7D has eleven circular ridges above the wire groove, and ten circular ridges below. (Note that this is the only Withycombe with circular ridges below the wire groove.)