Sentence:  ... that, abutting against the end of H, or nearly so, it will lock said bar as against a return or <WSD>rightwise</WSD> motion, and then said bar will be locked as against a reverse motion, and, being locked, its flop D cannot be rotated back, ... 
Meaning of the word marked with <WSD> tags:  Rightward (to or from the right side); on the right side.