Thus if a figure, e.g., a field, be in the form of a square,and its side be 40 feet long, its area is said to be 1600square feet, or contains 1600 little Squares, each a Foot every Way. See SQUARE and MEASURE. Hence, to find the Area of a Triangle, Square, Parallelogram, Re€tangle, Trapezium, Rhombus, Polygon, Circle, or other Figure, is to find the Magnitude or Capacity thereof in square Measures—To do which, see under the Articles TRIANGLE, SQUARE, PAKALLELOGRAM, RECTANGLE, TRAPEZIUM, RHOMBUS, POLYGON, CIRCLE, &c.
To find the Area of Fields, and other Inclosures; they first survey or take the Angles thereof, then plot them on Paper, and thus cast up their Contents in Acres, Roods, &c. after the usual manner of other plain Figures. See SURVEYING, PROTRACTING, &c. The Law by which the Planets move round the Sun, is this: that a Line or Radius drawn from the Centre of the Sun to the Centre of the Planet, always sweeps or describes Elliptic Areas proportional to the Times.
Thus, the Sun being supposed in S, and a Planet in A, (Tab. Astronomy, Fig. 65)
and letting it proceed in any given Time, to B. In such Progress, its Radius AS, will have described the Area ASB.
Suppose again, the Planet to be arrived to P ; then the Elliptic Space PSD being drawn equal to the other ASB, the Planet will move thro’ the Arch PD in the fame Time as thro’ the Arch AB. See PLANET and ELLIPSIS.
Sir I. Newton demonstrates that whatever bodies observe such a law in their motions about any other body, gravitate towards such body. See GRAVITATION, and NEWTONIAN PHILOSOPHY.
AREA is also used in Medicine, for a disease which makes the hair fall out. See HAIR.
The area is a general kind of depilation, and is distinguished into two kinds, Alopecia and Ophiasis. See ALOPECIA, OPHIASIS.