Surveying

In military mathematics, the art or act of measuring lands; that is, of taking the dimensions of any tract of ground, laying down the same in a map or drawing, and finding the content or area thereof. Surveying , called also geodæsia , is a very ancient art; it is even held to have been the first or primitive part of geometry, and that which gave occasion to, and laid the foundation of all the rest. Surveying consists of three parts: the first is the taking of the nece ary measures, and making the most nece ary observations, on the ground itself: the second is, the laying down of these measures and observations on paper: and the third, the finding the area or quantity of ground there laid down. The first is what we properly call surveying ; the second we call plotting , protracting , or mapping ; and the third casting up . The first, again, consists of two parts, viz. the making of observations for the angles, and the taking of measures for the distances. The former of these is performed by someone or other of the following instruments, viz. the theodolite, cir cum fer enter, semi-circle, plain table, or compa . The latter is performed by means either of the chain, or perambulator. The second branch of surveying is performed by means of the protractor, and plotting scale. The third, by reducing the several divisions, inclosures, . into triangles, squares, trapeziums, parallelograms, . but especially triangles; and finding the areas or contents or these several figures. See American Mil. Lib.