This will give you a start.
http://www.sheldonbrown.com/
On Tuesday, February 25, 2003, at 07:16 PM, Tom Sanders wrote:
> I'm almost holding my breath waiting for the much anticipated Lug
> history and display site that has been discussed on the list. I think
> lugs are my favorite parts of nice bikes. However every once in a
> while someone asks me a question about drop outs and I have to confess
> that I hardly know anything about them. I know from time to time I
> hear more experienced list members discussing different types and I
> nod sagely as if I knew what they are talking about, somewhat
> embarrassed by my ignorance. I may not be alone here. Is there a
> site where there is a time line and illustrations of different types
> of drop outs to peruse? Perhaps, if not, someone might put such a
> thing together? I even own a couple of bikes with unusual dropouts,
> and I have no idea just what they are.
> Abashed in Lansing, Mi
> Tom Sanders