OK, I'm home and have free time to look your coin up in the Hartill catalogue. The basic type is the "protruding head boo" variety, which dates roughly from 1761-1767. After 1726, the Board of Revenue controlled four mint facilities, all situated to the northeast of the Forbidden City in Beijing, called the North, South, East and West branches by their positions relative to each other. Your coin has the privy mark of the East Branch. The Hartill reference number, if you're curious, is 22.207.
Don't say "infinitely" when you mean "very"; otherwise, you'll have no word left when you want to talk about something really infinite. - C. S. Lewis