Help please with Nessen lamps  

I just bought a pair of chrome Nessen swing arm ( wall mounted ) lamps from a thrift store for $2.50 each - such a bargain. The problem is that they are missing the shades. They have the three thumb screws in the socket that would normally secure a bell-shaped, milk glass diffuser that would usually be topped off with a traditional shade. But because this is a swing lamp and not a stationary lamp, I can't figure out how it all would go together. Can anyone describe how to correctly complete these lamps? Pics would be great! Also, are these shades currently available anywhere?