Early rail cross-section (1830 -1840 ?)

[DonB]

I have been given a paperweight in the form of a clear plastic block encasing a cross-section of an early rail.

I was told that it was a memento presented to delegates at a conference under the auspices of the UIC (union Internationale des Chemans de Fer) probably in the early 1970s.

 

A search on Wikipedia ( http://en.wikipedia.org/wiki/Rail_profile )

 

showed a sketch of the rail form annotated as "single parallel" alongside a bull-head type called "double parallel"

 

 

I have not found any further details of when this rail section was in use, nor how it was held securely in service. It is difficult to tell positively through the plastic block, but I think it is cast iron. 

 

Any Ideas of when & how it was used??