83 
CLASSES-COMMUTATIVE. 
Classes: of curves, n, 569—83, v, 518, 521, vi, 11, xi, 629. 
Classification: of curves, v, 613—7; cubics aud quartics, vi, 525; quartic surfaces, vn, 244; nodal 
quartic surfaces, vn, 264—7 ; mathematical tables, ix, 424—5 ; cubic curves, xi, 478—80; quartic 
curves, xi, 480. 
Clausen, T.: Castillon’s problem, iv, 435—41. 
Clebsch, K,. F. A.: Steiner’s extension of Malfatti’s problem, n, 593; Pfaffian equations, iv, 515; 
singularities of curves, v, 476—7; developable surfaces, v, 518; Abelian integrals, v, 521; trans 
formation of plane curves, vi, 1—8, 593; Casey’s equation, vi, 67; binary quintie and sextic, vi, 
190; principle of correspondence, vi, 264; reciprocal surfaces, vi, 356; cubic curve in pencil of 
six lines, vi, 593—4; centro-surface of ellipsoid, vn, 130, vm, 316 ; quartic and quintie surfaces, 
vn, 245—51, 313; bicursal curves, vm, 182; transformation of unicursal surfaces, vm, 389; 
deficiency of surfaces, vm, 394; covariants, vm, 404; expression for elliptic integral of second 
kind, x, 27; concomitants of ternary cubic, xi, 343; tables for binary sextic, xi, 372; Abelian 
functions, xii, 102, 109; symbolic notation for qualities, xn, 347; seminvariants, xm, 362; Pfaff- 
invariants, xm, 405—14. 
Clifford, W. K.: powers of circles and spheres, i, 581; circle and ellipse, v, 561; conic, v, 562; 
triangles and polygons, v, 589 ; rational transformation between two spaces, vn, 222—4; quartic 
surfaces, vii, 246 ; compound combinations, x, 243; biquaternions, xi, 458; syzygetic relations among 
the powers of linear qualities, xm, 224—7; non-Euclidian geometry, xm, 481. 
Close : partitions of a, v, 62—5, 617 ; defined, v, 63. 
Close-planes: the term, vi, 330, 583—5. 
Close-points: the term, vi, 330, 339, 341, 583—5. 
Cnicnode: the word, vi, 330, 334, 361, 583—5, xi, 228, 631, 633; quartic and quintie surfaces, vn, 
245—51. 
Cnictrope : the word, vi, 330, 334, 583—5, 591, xi, 228, 631, 633. 
Cobezoutiants: defined, ii, 524. 
Cobezoutoids : defined, n, 524—5. 
Cockle, Sir James: resolvent product, iv, 309—13; on quintics, v, 53; theory of equations, xi, 520; 
invariants, xn, 390—1; criticoids, xm, 366, 367—8. 
Codazzi, D.: application of surfaces, xm, 253—64. 
Coefficients: of Legendre, I, 375—6; development of (1 +n 2 x) m/n , xm, 354—7. 
Cogredient: the term, iv, 607—8, xm, 46. 
Cohen, A.: relative motion, iv, 537, 586; rotation of solid body, iv, 573, 586. 
Cole, F. W.: on simple groups, xm, 533. 
Colink: the term, v, 521. 
Collins, M.: Lagrange’s theorem, n, 3; systems of circles, x, 566—7. 
Colour Groups : diagrams representing, x, 328—330, 403—5 ; the term, xii, 639—41. 
Colours: in maps, xi, 7—8. 
Colourset: the term, xii, 641. 
Columns: the term, xii, 353. 
Comberousse, C.: polyhedra, iv, 609. 
Combescure, E.: wave surfaces, xm, 238. 
Combinants: of qualities, n, 322; the term, n, 518, iv, 607—8, xm, 46; and ternary quadratics, 
iv, 352. 
Combinatory Analysis: magic squares, x, 38; compound combinations, x, 243—4; a problem of 
arrangements, x, 245—8; note on Mr Muir’s solution, x, 24.9—51; the game of mousetrap, x, 
256—8; Sylvester’s work in, xm, 47 ; (see also Partitions). 
Commutants: the term, i, 584, n, 19, 26, iv, 594, 599—600, xm, 46; property of, v, 495—7. 
Commutative: the term, xii, 461; (see also Groups). 
11—2