Here are some interesting old jean patents.

The image above is of a continuos fly made from one piece of denim. Most flys are made from two separate pieces. I am in the process of deconstructing an old pair of Nudies for pattern making ideas and information gathering purposes. I will show how a two part fly is constructed in an up coming post. Warehouse's Heller's Cafe reproduction jean (pictured below the patent) has a continuous fly. This is supposed to be stronger than a two part fly because it doesn't rely on threat/stitching to hold the fly together.

This patent shares a lot in common with the one above it but it utilizes a metal loop at the bottom of the fly. I love this idea but worry about the comfort level. Having a metal bar so close to the family jewels might cause problems. I don't know of any jeans being made today that have this feature. Its scarcity makes me think it was a better idea in theory than in reality

This is a non-rivet reenforcement patent. It shows any fabric being sewed onto the stress points in places where you usually see rivets. It could be leather, extra denim, ect. The modern reproductions jeans (pictured below the patent) are again Warehouse. This time however its there Duck Digger line.

This is another very cool pocket reinforcement idea. In stead of adding fabric, the top layer of fabric is sewn over the stress points. I have never seen a reproduction of this but I really like the idea. It is both esthetically appealing and structurally sound.