paul womack wrote:
> This design sounds worthy of making...

The book Kirk linked to (Animal Traps and Trapping, by James A. Bateman, 2003)
has a worrying statement;

"When the patent for this trap expired, many imitations appear to
have been marketed, but mostly these were inefficient compared with
the original. An acceptable variation was made for a number of
years by the firm of Duke, Waring, Crisp & Co, at the Soho wireworks,
in London."

Now, the makers of the the "inefficient versions" presumably
had access to the originals, ad could make a close copy,
and yet they still failed.

This leads to me to suspect two possibilities

* they cheapened the manufacture by cutting corners that lessened
   the operational quality

* the original is simple in principle, but the the details, sizes
   weights etc all need fine tuning to work well.

It could be both, of course. The second reason would be a strong objection
to creating a reproduction based on diagrams "in principle",
and an overall shot from the web.

Which is all the information we currently have :-(

  BugBear