On the left is the Hemingray CD 152 [085] "Brookfield Style" mold, on the right is the CD 157 "teepee", and taking center stage is my personal favorite Hemingray style, the CD 169 Type I!

So why are these three grouped together? Well, take a look at them. All three styles are almost identical from the wire groove up. Coincidence? I doubt it, since all three of these Hemingray styles were the product of a c.1910 experiment by AT&T to come up with a new standard insulator. The CD 152 won out, but the CD 157 was produced as well. The Type I prototype wasn't so lucky; there are only about 4 or 5 known to have survived the stress tests.