Normal \Nor"mal\, a. [L. normalis, fr. norma rule, pattern, carpenter's square; prob. akin to noscere to know; cf. Gr. ? well known, ? gnomon, also, carpenter's square: cf. F. normal. See Known, and cf. Abnormal, Enormous.]

1. According to an established norm, rule, or principle; conformed to a type, standard, or regular form; performing the proper functions; not abnormal; regular; natural; analogical.

Deviations from the normal type. --Hallam.

2. (Geom.) According to a square or rule; perpendicular; forming a right angle. Specifically: Of or pertaining to a normal.

3. (Chem.) Standard; original; exact; typical. Specifically:
   (a) (Quantitative Analysis) Denoting a solution of such strength that every cubic centimeter contains the same number of milligrams of the element in question as the number of its molecular weight.
   (b) (Chem.) Denoting certain hypothetical compounds, as acids from which the real acids are obtained by dehydration; thus, normal sulphuric acid and normal nitric acid are respectively S(OH)6, and N(OH)5.
   (c) (Organ. Chem.) Denoting that series of hydrocarbons in which no carbon atom is united with more than two other carbon atoms; as, normal pentane, hexane, etc. Cf. Iso-.

Normal equations (Method of Least Squares), a set of equations of the first degree equal in number to the number of unknown quantities, and derived from the observations by a specified process. The solution of the normal equations gives the most probable values of the unknown quantities.

Normal group (Geol.), a group of rocks taken as a standard. --Lyell.

Normal place (of a planet or comet) (Astron.), the apparent place in the heavens of a planet or comet at a specified time, the place having been determined by a considerable number of observations, extending perhaps over many days, and so combined that the accidental errors of observation have largely balanced each other.

Normal school, a school whose methods of instruction are to serve as a model for imitation; an institution for the training of teachers.

Source: Webster's Revised Unabridged Dictionary (1913)
 

Normal \Nor"mal\, n. [Cf. F. normale, ligne normale. See Normal, a.]

1. (Geom.) Any perpendicular.

2. (Geom.) A straight line or plane drawn from any point of a curve or surface so as to be perpendicular to the curve or surface at that point.

Note: The term normal is also used to denote the distance along the normal line from the curve to the axis of abscissas or to the center of curvature.

Source: Webster's Revised Unabridged Dictionary (1913)
 

Fault \Fault\, n.

1. (Elec.) A defective point in an electric circuit due to a crossing of the parts of the conductor, or to contact with another conductor or the earth, or to a break in the circuit.

2. (Geol. & Mining) A dislocation caused by a slipping of rock masses along a plane of facture; also, the dislocated structure resulting from such slipping.

Note: The surface along which the dislocated masses have moved is called the

fault plane. When this plane is vertical, the fault is a

vertical fault; when its inclination is such that the present relative position of the two masses could have been produced by the sliding down, along the fault plane, of the mass on its upper side, the fault is a

normal, or gravity, fault. When the fault plane is so inclined that the mass on its upper side has moved up relatively, the fault is then called a

reverse (or reversed), thrust, or overthrust, fault. If no vertical displacement has resulted, the fault is then called a

horizontal fault. The linear extent of the dislocation measured on the fault plane and in the direction of movement is the

displacement; the vertical displacement is the

throw; the horizontal displacement is the

heave. The direction of the line of intersection of the fault plane with a horizontal plane is the

trend of the fault. A fault is a

strike fault when its trend coincides approximately with the strike of associated strata (i.e., the line of intersection of the plane of the strata with a horizontal plane); it is a

dip fault when its trend is at right angles to the strike; an

oblique fault when its trend is oblique to the strike. Oblique faults and dip faults are sometimes called

cross faults. A series of closely associated parallel faults are sometimes called

step faults and sometimes

distributive faults.

Source: Webster's Revised Unabridged Dictionary (1913)