Sentence:  And whosoever shall refuse any one of his three Essays [...] shall be deem'd a "Helot" or <WSD>public Servant</WSD>, shall pay a fifth part of his yearly Revenue, besides all other Taxes, to the Common-wealth for his Protection, and be incapable of bearing any Magistracy except such as is proper to the Law. 
Meaning of the word marked with <WSD> tags:  Someone who labours for the public good; a convict assigned to work on public projects. (from 16th c.)