When did they start, when did they fall out of favor?
Were they popular outside of the rich?
This would probably take hitting the etiquette and dance books. You do know the online collection at the Library of Congress? Fabulous to check these things.
My question here is, were they a custom of the wealthy, or a middle-class habit? Was their use confined to one country, or did it start in A and linger longest in B? This, too, can affect dates of usage.