Math. [CONTRA- 2.] Having, as two conics or conicoids, the sums of the squares of two corresponding axes equal: opposed to CONFOCAL conics, etc., in which the differences are equal.
1866. Sylvester, in Phil. Trans., 760. Contrafocal ellipsoids, the sums of whose squared axes are the same in all three directions.
1868. Routh, Rigid Dynamics, 358. The momental ellipsoids of these bodies are contrafocal, i. e. have the sum of the squares of any two principal diameters the same in each ellipsoid.
Hence Contrafocalism, the property of being contrafocal.
1866. Sylvester, in Phil. Trans., 771.
