'Snap' Lock verses 'Screw Key' Lock

In the previous post with the 1904 Hiatt Catalogue a few things struck me about about the descriptions which jar with how we describe them today. 'Snap' is obvious because you don't need a key to lock them (Darbies) but 'Screw Key Lock' is what collectors call a Plug Lock even though both use a key that screws in!   I like the 'Snap' description but I don't like the 'Screw Key' for Plug locks. They were still offering 'Plug' leg irons in 1904!

N Collar, Ass, Colt and Horse hobbles. 
The name of N collar is unfortunate and would have come from bygone days. But what exactly was it used for in 1904 - tethering animals?
The single 'Plug' locks came in sizes to fit an Ass, Colt or Horse and so are not intended for humans.
'Snap' horse hobbles, leather covered, with chain would presumably be a single darby leg cuff on a chain.

A question for horse owners. Would a single leg cuff be used for simple restraint as opposed to a double cuff used to hobble while performing a procedure on a horse?

https://en.wikipedia.org/wiki/Hobble_(device)#:
 
https://en.wikipedia.org/wiki/Legcuffs

Paul, i can't see where a single hobble would ever be used on a standing animal, as it could lead to the animal braking it's own leg, but possibly be used on a laying down animal for a medical process to hold up a leg!

LK D~D

Obviously they were sold singly for such use, but how were they used? ie; In combination with a non-locking leather double hobble as used today or something even simpler?
Because they were lockable, they were an anti-theft devise, not a medical device which did not need to lock, but the leather would have been useful with a struggling animal or if used for extended periods of time.

Since Hiatts were a British company, it's possible (sadly) that in some areas of the commonwealth, notably some countries in Africa, India, Burma etc, that slavery may have still been common in 1904, just a guess.

I did some more digging... at the very least South Africa, sadly.

The marketing terminology and the products were likely to be also in the use in the USA during the same time frame.
 
>>>>>> 
 
By the first years after 1900, tens of thousands of African American men and boys, along with a smaller number of women, had been sold by southern state governments. An exponentially larger number, of whom surviving records are painfully incomplete, had been forced into labor through county and local courts, backwoods justices of the peace, and outright kidnapping and trafficking. The total number of those re-enslaved in the seventy-five years between the end of the Civil War and the beginning of World War II can’t be precisely determined, but based on the records that do survive, we can safely say it happened to hundreds of thousands. How many more African Americans circumscribed their lives in dramatic ways, or abandoned all to flee the South entirely, to avoid that fate or mob violence?
 
https://washingtonmonthly.com/magazine/ ... y-slavery/

Thanks James and Ian. 
Assuming we are talking about the collars, I really had not considered modern slavery. Officially it ended in England in 1834. But I guess that those inclined to enslave might also be inclined to use the collars. That really is food for thought.

By the first years after 1900, tens of thousands of African American men and boys, along with a smaller number of women, had been sold by southern state governments. An exponentially larger number, of whom surviving records are painfully incomplete, had been forced into labor through county and local courts, backwoods justices of the peace, and outright kidnapping and trafficking. The total number of those re-enslaved in the seventy-five years between the end of the Civil War and the beginning of World War II can’t be precisely determined, but based on the records that do survive, we can safely say it happened to hundreds of thousands. How many more African Americans circumscribed their lives in dramatic ways, or abandoned all to flee the South entirely, to avoid that fate or mob violence? Ian.
Mike from Canada:
Ian, thanks for that link. Incredible.
It explains something that I couldn't figure out. My community in Southern Ontario was part of the top end of the Underground Railway. From 1858 hundreds of escaped slaves made it to our community. What I didn't understand was why a lot of the black kids I went to school with only had a short connection with Canada. Their parents came in the 1920s and 30s. Now I understand why a lot of them left the USA.
Mike