A first note on this subject, viz., the elimination of x, y, z from the equations

was communicated to the Society in April 1892. By reason of my immediate departure for South Africa, the manuscript was not prepared for the press, and the paper was consequently not printed until this year. In the meanwhile, both Professor Tait and Lord M'Laren had written notes on the subject, under the impression, I fear, that the object of my original paper was to obtain in any way an easy solution of the problem.