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EQUATOR-FERRERS. 
Equator: action of gravity at the, ix, 241—3. 
Equilibrium: of four forces, v, 540—1, ix, 201; of skew surface, xi, 317—22. 
Equimomental Surfaces (see Surfaces). 
Equipollences : Bellavitis, xn, 473—4. 
Equipollent: the term, xn, 473. 
Equipotential Curve : hi, 258—61. 
Essential Singularity of Function: iv, 150. 
Eta-Functions: product, xn, 584—6; (see also Theta Functions). 
Euclid: space of, xi, 434—7; evolution of geometry, xi, 446; proof of I, 47, xi, 557. 
Euler, L. : rotation of solid body, I, 237, iv, 566, 567—9, 587, VI, 135—46; involution, I, 259; elliptic 
functions, i, 366; skew determinants, n, 214; transformation of coordinates, n, 497, iv, 553—7, 587; 
sums of series, hi, 127; indeterminate equations, hi, 205—7; polyhedra, iv, 84, 86—7, v, 62—5, 617; 
Determinate Orbitce Cometce, iv, 519, 587; problem of two centres, iv, 525—7, 587; three mutually 
attracting bodies in right line, iv, 538—9, 587; motion of three bodies, iv, 540, 587; inertia, iv, 
562; kinematics of solid body, iv, 580, 587; rotation formulae, v, 537; differential equation of, vn, 
261—2, ix, 592—608, xi, 68—9 ; binomial theorem, vm, 463; mathematical tables, ix, 463—6, 471—2, 
477—8, 481, 487; theorem on sums of squares, xi, 294; partitions, xi, 360, xn, 219; intersections of 
cubic curves, xi, 449; gamma function, xi, 535—6; eight-squares theorem, xn, 465; Latin squares, 
xih, 55; differential equation of, integrated by Richelot, xm, 525—9. 
Evans, A. B. : llegen’s tables, x, 586. 
Evectant: of qualities, n, 321. 
Evector: of qualities, ii, 321. 
Evolutes: theory of, v, 473—9; and parallel curves, vm, 31—45; nodes of, vm, 329, 351. 
Evolution : of geometry, xi, 445—8. 
Ewing, J. A. : curve-tracing mechanism, xm, 505. 
Excuboquartic: defined, v, 10, vii, 99; curves, vi, 87—8, xi, 9—13. 
Exoscopic : the term, i, 588. 
Expansions: in multiple sines and cosines, i, 19—24, 583; in Laplace’s coefficients, i, 375—6; of true 
anomaly, m, 139—42; numerical, iv, 470—2. 
Expectation: problem and solution in, x, 587; (see also Probability). 
Experience and Cognition: xi, 431. 
Exponential Functions: and double theta functions, x, 184—5; the term, xi, 524—7. 
Extension: in conformal representation, xi, 78. 
Extent: the term in seminvariants, xm, 269, 363. 
Extraordinaries: and non-commutative algebras, i, 128—31, 301; the term, xn, 60, 461. 
Facients: defined, n, 221, iv, 604, vi, 464. 
Factions: the term, ix, 426. 
Factorial Expressions: summation of, hi, 250—3. 
Factorials: developments of, n, 98—101, 594; problems, v, 574, vn, 597; binomial theorem and deriva 
tions, vm, 463—73 ; maxima of certain functions, vm, 548—9. 
Factors, Special: the term, i, 337. 
Facultative: the term, vi, 156, 365; lines of cubic surfaces, vi, 450. 
Facultative Points: of Sylvester, xm, 46. 
Family of Quadrics: envelope of, x, 589. 
Family of Surfaces: part of orthogonal system, vm, 269—91. 
Fermat, P. de: theorem of, xi, 457, 597, 611, 615—6. 
Ferrers, N. M.: conjugate partitions, n, 419 ; area of conic, hi, 143—8; correspondence, x, 290; Legendrian 
coefficients, xii, 563. 
C. XIV. 
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