J. I. Thornycroft's paper on the 'Most Suitable Propeller for Shallow Draught.' read at the 1885 meeting of the Institution of Naval Architects was to a certain extent the continuation of his paper on the same subject read at the 1883 meeting of the Institution of Naval Architects. In the discussion that followed Arthur Rigg agreed with J. I. Thornycroft's conclusions but claimed to be the original inventor of the guide blade propeller having read papers on the subject before the Institution of Naval Architects in 1867 and 1868.