anomaly

[In Ger. & Fr. anomalie; Sp. anomalia, a nom alidad. From Gr. άνωμαλία ( anōmali a ) = unevenne , irregularity, deviation from rule; ἀνώμαλος ( anōmalos ) = uneven, irregular; a, av, priv., and ὁμαλός (homalos) = even, smooth; ὁμός (homos) = one and the same.] [ANOMALOUS.] A. Ordinary Language: Gen.: Deviation from rule; irregularity. "As Profe or Owen has remarked, there is no greater anomaly in nature than a bird that cannot By."-Darwin: Origin of Species, ch. v. "The truth is that the dispensing power was a great anomaly in politics."-Macaulay: Hist. Eng . , ch. ii. B. Technically : 1. Astron. The deviation in a planet's course from the aphelion or apogee. It is of two kinds, the true and the mean anomaly. The true is that which actually takes place. The mean is the angular motion which would have been performed had the motion in angle been uniform instead of the motion in area. (Herschel: Astron ., 5th ed., § 499.) Astron. Excentric Anomaly: "An auxiliary angle employed to abridge the calculations connected with the motion of a planet or comet in an elliptic orbit. If a circle be drawn, having its centre coincident with that of the ellipse, and a diameter equal to the transverse (major) axis of the latter; and if from this axis a perpendicular be drawn through the true place of the body in the ellipse to meet the circumference of the circle, then the excentric anomaly will be the angle formed by a line drawn from the point where the perpendicular meets the circle, to the centre, with the longer diameter of the ellipse." ( Hind .) Describe the circle ABCD, so that its centre L shall coincide with that of the ellipse, AECF, in which the planet P moves, and its diameter A cbe the longer axis of the IMG:content-0559.png:[blocks in formation] ellipse. Let's be the position of the sun in one of the foci of the ellipse, then a is that of the planet when in perihelion, and c that which it occupies when in aphelion. Join Ps, then the angle PALis the true anomaly. Proximity to the sun made the planet travel more quickly at a than at c. If the rate had been uniform, it would not have reached P. Let it be supposed that it would have been only at E, then A SE is its mean anomaly. Let fall PR a perpendicular to AC from P; produce it in the other direction to B in the circumference of the circle; join BL, then ALB is the excentric anomaly In calculating the motion of the moon, the earth is supposed to be at s, as it is also held to be when inquiry is made into the apparent course of the sun through the ecliptic. 2. Music : A small deviation from a perfect interval, in tuning instruments with fixed notes; a temperament.