I actually found three caps from England and France but I think only one is from a carriage. The Joseph Matthews cap from Leeds is the largest at 3 1/8" diameter by 2 5/8"high, very thick and heavy unplated brass. I love the name which appears to be hand etched into the cap. The small L. Renault Billancourt cap is 2 5/16" diameter by 2 1/4" high, newer with nickel plating and a stamped name but still quite heavy. The last is the Wolseley Motor Co. Ltd. Birmingham at 3 7/8" wide by only 1 5/8" high, beautifully machined and detailed with nickel plating and male threads for a large hub. Particularly fascinating are the diagonal broaching or machining marks at the bottom of the name letters, does that mean they were done after the cap was built? I'd love to know the age of these caps, I much prefer these early machining-intensive styles to the later low-detail stamped by the thousands versions.