Sentence:  if any thing of that nature be brought in, and desired to be lodged with the Society [...] they should be obliged to shew it first to the President (for fear of lodging <WSD>unknownly</WSD> ballads and buffooneries in these scoffing times), and that then it should be sealed up 
Meaning of the word marked with <WSD> tags:  (unknowingly), without knowledge; without intent.