The shoes have been featured at Kottke, BoingBoing, Neatorama, and a dozen more places in recent days, most of which reprint text from a 1922 newspaper article describing a method used by moonshiners to avoid detection:
The cow shoe is a strip of metal to which is tacked a wooden block carved to resemble the hoof of a cow, which may be strapped to the human foot. A man shod with a pair of them would leave a trail resembling that of a cow.The Holmes story was "The Adventure of the Priory School." I had to look up the context:
The shoe found was picked up near Port Tampa where a still was located some time ago. It will be sent to the prohibition department at Washington. Officers believe the inventor got his idea from a Sherlock Holmes story in which the villain shod his horse with shoes the imprint of which resembled those of a cow's hoof.
There is one other small point upon which I desire some light. This fellow Hayes had shod his horses with shoes which counterfeited the tracks of cows. Was it from Mr. Wilder that he learned so extraordinary a device?"But while searching that, I found an example of a Holmes deduction that was inaccurate. This from The Urban Country Bicycle Blog:
The Duke stood in thought for a moment, with a look of intense surprise on his face. Then he opened a door and showed us into a large room furnished as a museum. He led the way to a glass case in a corner, and pointed to the inscription.
"These shoes," it ran, "were dug up in the moat of Holdernesse Hall. They are for the use of horses, but they are shaped below with a cloven foot of iron, so as to throw pursuers off the track. They are supposed to have belonged to some of the marauding Barons of Holdernesse in the Middle Ages."
Photo credit: Library of Congress.