1779. Godsall's parallel rods (fig. 420.) consist of two rods (a and b), six feet long, and two inches wide. Into a two strips, fourteen inches long, are firmly mortised, at right angles; these pass through b, and, by means of wooden pins, the rods are secured by them at the required distance apart; c is a handle fixed to the rod a at a right angle. When the bed is raked level, and edged, after having the necessary margin along the side, the rod a is placed where the outside row is to be planted; the instrument must then be pressed slightly with the foot, when it will leave two parallel impressions. The rods must afterwards be shifted on in a direct line, always placing their ends, as a guide, about a foot along the previous marks, and then pressing them as before, till the operator arrives at the end of the bed. In returning, the rod a must be placed in the furrow, before made by b; and so on, till the whole bed is marked longitudinally. By applying the rods in a similar manner across the bed, it is formed into squares; and by this method a bed, twenty feet by four feet, may be accurately marked in five minutes. The instrument is also useful as a square; and may be employed as a level, by attaching a plummet line to the top of the handle. The rod b is divided into feet and inches, and is easily detached for sundry purposes.