Sir Arthur Conan Doyle created a sleuth who succeeded where others failed by employing systematic powers of observation and inference.
Additionally, Holmes was a student of trivial facts pertinent to his work.
Here's a few furniture tips that may prove useful to you.
Round section nails, known commonly as wire nails, were invented in France c.1830 and had ground points and hand-made heads.
As such its form appears unchanged over the centuries and unless it can be extracted and tested will be of little use for dating.
Obviously it points to an equine connection and is more likely to be found in farm buildings than elsewhere which also indicates an ad hoc repair rather than a professional one.
The machine flipped the bar after each cut in order to ensure even sides.