By  Rectangular  System In the early days (from 1785) of the United States, provisions were made to subdivide territorial lands into  townships  and  sections  thereof,  along  lines running with the cardinal directions of north-south, east-west. Later, as additional lands were added to the public  domain,  such  lands  were  subdivided  in  a similar  manner. However, these methods of subdividing lands do not  apply  in  the  eastern  seaboard  (original  13  states) and in Hawaii, Kentucky, Tennessee, Texas, and West Virginia. For laws regulating the subdivision of public lands and the recommended surveying methods, check the instruction manual published by the Bureau of Land  Management,  Washington,  D.C. By  Plane  Coordinates For  many  years  the  triangulation  and  traverse monuments of various domestic and foreign survey agencies   have   been   defined   by   their   geographic positions; that is, by their latitudes and longitudes. Property  corners  might  be  definitely  fixed  in  position in  the  same  way.  The  necessary  computations  are involved, and too few land surveyors are sufficiently well versed in the theory of geodetic surveying for this method to attain widespread use. In recent years, plane coordinate systems have been developed and used in many states and in many foreign countries. These grid systems  involve  relatively  simple  calculations,  and their use in describing parcels of land is increasing. Every state in the American Union is now covered by a statewide coordinate system commonly called a  grid system. As  with  any  plane-rectangular  coordinate  system, a   projection   employed   in   establishing   a   state coordinate system may be represented by two sets of parallel  straight  lines,  intersecting  at  right  angles.  The network thus formed is the  grid. A system of lines representing  geographic  parallels  and  meridians  on  a map projection is termed graticule. One set of these lines is parallel to the plane of a meridian passing approximately  through  the  center  of  the  area  shown  on the  grid,  and  the  grid  line  corresponding  to  that meridian is the  Y-axis of the grid. The  Y- axis is also termed the central meridian of the grid. Forming right angles with the Y- axis and to the south of the area shown  on  the  grid  is  the  X-axis.  The  point  of intersection of these axes is the  origin of  coordinates. The position of a point represented on the grid can be defined  by  stating  two  distances,  termed  coordinates. One  of  these  distances,  known  as  the  X-coordinate, gives the position in an east- and -west direction. The other distance, known as the  Y-coordinate, gives the position  in  a  north-   and-  south   direction;   this coordinate  is  always  positive.  The  X -coordinates increase in size, numerically, from west to east; the Y -coordinates increase in size from south to north. All X -coordinates in an area represented on a state grid are made   positive   by   assigning   the   origin   of   the coordinates:   X = 0 plus a large constant. For any point, then, the  X -coordinate  equals  the  value  of  X adopted for the origin, plus or minus the distance (X´) of the point east or west from the central meridian  (Y -axis); and  the  Y -coordinate  equals  the  perpendicular distance to the point from the  X -axis. The linear unit of the state coordinate systems is the foot of 12 inches defined  by  the  equivalence:  1  international  meter = 39.37 inches exactly. The linear distance between two points on a state coordinate  system,  as  obtained  by  computation  or scaled from the grid, is termed the grid length of the line  correcting  those  points.  The  angle  between  a  line on the grid and the Y -axis, reckoned clockwise from the south through 360°, is the grid azimuth of the line. The  computations  involved  in  obtaining  a  grid  length and  a  grid  azimuth  from  grid  coordinates  are performed  by  means  of  the  formulas  of  plane trigonometry. A property description by metes and bounds might include points located by coordinates as follows: “Commencing  at  U.S.  Coast  and Geodetic  Survey  Monument  ‘Bradley, Va’, having coordinates y = 75,647.13 ft and  x  =  35,277.48 ft, as based on the Virginia   Coordinate   System,   North Zone, as are all the coordinates, bearings, and distances in this description; thence S  36°30´E,  101.21  ft  to  the  intersec- tion of Able Street and Baker Avenue, whose coordinates are y = 75,565.77 ft and x = 35,337.45 ft, . . . .” By  Blocks,  Tracts,  or  Subdivisions In many counties and municipalities the land of the  community  is  divided  into  subdivisions  called blocks,  tracts,  or subdivisions.  Each  of  these subdivisions is further subdivided into  lots. Blocks and tracts usually have numbers, while a subdivision usually has a name. Each lot within a block, tract, or subdivision usually has a number. 10-32