388 Scientific Proceedings, Royal Dublin Society. 
The four polar planes of the conical points with respect to 
== 0 consist of two pairs of parallel planes, and any two not 
parallel are equally inclined to the circular sections of the ellip- 
soid of elasticity. I have calculated the volume of a singular 
tangent cone cut off by the polar plane of its vertex with reference — 
to S=0; its value appears to be 
xr we (@ oe b’)? (0? = ce)? 
which I leave to the reader to verify. 
