These watches have been made for the Chinese market around 1850-1880. Most of them have been manufactured by Swiss watchmakers like Bovet. Their nice movements (with duplex or lever escapement) are fully engraved. Currently they are quite affordable, but I have noticed that the prices are rising. The collectors really like them. In fact, they were undervalued some years ago...
The most interesting models have a duplex escapement : the second hand moves every second like a quartz watch.
The pendant is characteristic
The nice movement with duplex escapement
An other one
A nice pair cased model with a very special movement
A rare gold model made by Fiebelmann (Rotterdam)
And finally, a very rare animated erotic model with lever escapement
<mod edit: Sorry, but those pictures aren't suited for a family-friendly forum!>
I hope that you have appreciated this little article