This is one of the clearest pictures of insulators I've seen. There are only about a dozen or less pictures in which a threadless insulator in service is clearly seen. If you look closely, there are 3 - 737's on the flimsy, crude (the bark is still on it!), pole in the foreground, a wire is on the lowest one. This picture was taken during the Civil War, circa. 1861-1865.