Sentence:  We must keep them to the fact that the duty is one and three quarter <WSD>farthings</WSD>, or nearly a half-penny in the pound and no more, and any one who tries to work it out any other way is not acting fairly in the matter. 
Meaning of the word marked with <WSD> tags:  Former British unit of currency worth one-quarter of an old penny; or a coin representing this.