Acording to the inscription on left of the value, it's probably "China" but the design remember me some kind of "Telegraph" stamp or telecomunication, or a fiscal stamp...
The Ningpo postmark is Chinese. The stamp is from Hong Kong and the cancel of dots is a ship postmark. The letter C is a code for Wednesday. You will find the stamps listed under Hong Kong Treaty Ports in SG Commonwealth cat and in Yang's cat on Hong Kong. Webb lists postmarks of China, but it is a difficult book to find.
Moderator Note: Added Country Name to the Title for clarity
