NODAL-NUTATION. 
114 
Nodal Residue of Scrolls : v, 169—70, 181—3, 184, 187. 
Nodal Total of Scrolls: v, 169—70, 183—9. 
Node-couple: defined, n, 29, iv, 22, xi, 227 ; curve, and plane, and torse, vi, 355, 582—5; torse, 
vi, 601. 
Node-cusp : v, 265—6, 618. 
Node-form : the term, vn, 274. 
Nodes : the term, n, 28, iv, 22, 27, 181, v, 295, xi, 468 ; elimination of, in three bodies, iv, 551, v, 23 ; 
number on quartic surface, vii, 133—81; quartic surface with twelve, xra, 1—2. 
Node-tangent: defined, ii, 29—32. 
Node-triplet: the term, ii, 30. 
Nodo-focus : of bicircular quartic, vi, 522—3, 523—6; the term, ix, 264. 
Non-commutative Algebra (see Algebra). 
Non-Euclidian Geometry, Memoir on: introduction, xm, 480—1; geometrical notions, xm, 481—9 ; 
point, line, and plane coordinates, general formulae, xm, 489—91 ; the absolute, xm, 491—5 ; 
distance of a point and line, xm, 495—7; distance of a plane and line, xm, 497; theory of two 
lines, xm, 497—504. 
Non-Euclidian Geometry: vm, 409—13, xn, 220—38; (see also Hypergeometry). 
Non-facultative Space : vi, 156. 
Non-scrolar Surfaces: quartic and quintic, vn, 245. 
Non-unitariants: the term, xm, 265. 
Non-unitary Symmetric Functions: and seminvariants, xn, 239, 275, xm, 267—98; tables, xn, 
273—4. 
Norm : and polyzomal curves, vi, 474, 573—5. 
Normal Elementary Integral: of differential equation, xii, 396—7, 444. 
Normals: in Ency. Brit., xi, 564—5; (see also Conics). 
Normal Variables: in dynamics, ix, ill. 
Notation: algebraic functions, n, 185—8 ; matrices, n, 185—8 ; qualities, n, 223; for disturbing function 
compared, in, 310—8; qualities and abstract geometry, vi, 464—6; differential equations, x, 95—7; 
for double theta functions, x, 497 ; theta functions, xi, 47—9, 243—5; umbral, xm, 301—6. 
Nother, M.: curves in space, v, 613—7; rational transformation, vii, 255; deficiency of surfaces, vm, 
395 ; sextic curve, ix, 504—7 ; classification of curves, xi, 451; Abelian function, xii, 149. 
Novel-reading : at Cambridge by Cayley, vm, x—xi, xxiii. 
Nullity : Sylvester’s theory of, xm, 47. 
Number : time, and space, v, 292, 620, xi, 442—4 ; theory of equations, xi, 502. 
Numbers: a theorem of Lejeune-Dirichlet’s, n, 47—8; tables of binary cubic forms, viii, 51—64; use 
of Bernoulli’s, in analysis, ix, 259—62; arrangements of, x, 570; Sylvester and Hammond on 
Hamiltonian, xm, 48; (see also Partition of Numbers). 
Numbers, Theory of, in Ency. Brit.: xi, 592—616; ordinary and complex theories, xi, 592—3; ordinary 
theory, xi, 594—609, 615—6 ; theory of forms, xi, 604—9 ; complex theories, xi, 609—16. 
Numbers, Theory of: Pellian equation, iv, 40—2, ix, 477—8, xi, 615, xm, 430—67; composition of, 
iv, 70—1, 78—9; specimen table, vi, 83—6; x p —l = 0, trisection and quartisection, xi, 84—96; 
x p -l-0, and quinquisection, xi, 314—6, xii, 72—3; H. J. S. Smith on, xi, 429; imaginaries, xi, 
444—5; evolution, xi, 455—6; Wilson’s theorem, xii, 45; Sylvester on, xm, 47; (see also Partition 
of Numbers). 
Numerative Geometry: Schubert’s, xi, 281—93. 
Numerical Equations: x, 3—6. 
Numerical Expansions: iv, 470—2. 
Numerical Generating Function: x, 339, 408. 
Nutation : note on theory of, ix, 194—6.