isogon Geom. rare—0.
(ˈaɪsəgɒn)
In 7–8 erron. isagon.
[f. Gr. ἰσογώνι-ος equi-angular.]
A figure having equal angles.
| 1696 Phillips (ed. 5), Isagon. So 1700 in Moxon Math. Dict.; 1721 in Bailey. |
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Restrict Geom. rare—0 to sense in Dict. and add: 2. [ad. G. Isogone (J. W. Sandström 1909, in Annalen d. Hydrogr. und Maritimen Meteorol. XXXVII. 242), f. Gr. ἰσογών-ιος equiangular.] A line (imaginary or on a map, etc.) joining the points at which some specified angle has a particular value; spec. in Phys. Geogr., an isogonic line.
| 1911 V. Bjerknes et al. Dynamic Meteorol. & Hydrogr. II. vii. 63 We have agreed to represent observed directions by numbers... We can draw curves joining the points where these numbers are equal. In all points of such a curve the vector will have the same direction... These curves may therefore be called isogonal curves or isogons. 1940 Chambers's Techn. Dict., Isogonic line, isogon, an imaginary line drawn through points of equal magnetic declination at any time. 1958 Jrnl. Brit. Interplanetary Soc. XVI. 342 We can now trace lines of equal configuration in our diagram, which we call isogons. 1975 Nature 14 Aug. 571/2 The use of isogons in the analysis of fold geometry can only be fully applied if the limb dip at the inflection points of the inner and outer arcs is identical. 1976 S. E. Stiegeler Dict. Earth Sci. 152/2 Isogon, 1. A line joining points of constant wind direction. 2. A line joining points of equal magnetic variation. |