This is an old Chinese carpentry tool. It was used the same as today's carpenter's "chalk line". The bowl would be filled with powdered charcoal and the string would be pulled through the bowl, and a straight line would be snapped. The string would be rewound by tuning the "crank handle".
Older carpenters frequently made their own tool and the carving on this one is very well done, a dragons head floating in a wave pattern. Note the hand made string...very rare. This piece is almost 10" long. The thin lip of the wheel does have a few minor nicks but this is a piece which was made and clearly used by a serious Chinese craftsman.