I have not been able to view documentation of any subsequent challenges
that were made on this issue.
Without further contemporary evidence, what are we left with?
might appear that Grover and Baker simply pinched Wilson's described
idea, and patented it for themselves later that same year. The
problem with this is that Grover and Baker's patent was sealed
just seven days after Wilson's. Logically, it seems hard to believe
that Grover and Baker could have seen a copy of Wilson's new patent,
drawn up their own, and have it submitted and granted all within
one week. It's worth remembering that Grover and Baker's patent
also contains the other significant modifications to their own
machine, which they would have wanted to patent anyway.
US patents of this period only give the approved date, unlike
UK patents, which also show "applied for" dates. I believe
very dusty records do still exist in the USA, which contain information
on submission dates, etc., but these are not easily accessed.)
it just be that Grover and Baker, and Wilson conceived the principle
of four motion feed at approximately the same time, it was after
all a period of very rapid sewing machine development. A second
and far more plausible explanation could be that Wilson was in
fact marketing a machine which incorporated the new feed some
time before his '52 patent was submitted. Messrs. Grover and Baker,
after possibly seeing a production machine, had then seized upon
this feature as one of great potential and decided to patent it