Here is a CD 283 insulator with corresponding wooden pin that was used on a 22,000 V. enclosed brick substation.

The wire was secured on the top most portion wire grove of the insulator and the ridges on the crown provided increased electrical resistance. The "Provo" series insulators were a very unusual design that is attributed to W. Converse and were used on pioneering power lines in the 1890s-1900s. The high voltage lines using these type of insulators were quickly upgraded making it highly unlikely to find a "Provo" type glass insulator still in use. Glass simply did not have the mechanical strength and resistance to fracturing from the heat of a power arc/ flashover. The one advantage it did have was that is was significantly cheaper than porcelain insulators.