482 SCIENCE OF AGRICULTURE. Part II. 



cannot be adopted on account of the height of the inequalities, the line must either be 

 formed along the summits of these inequalities, which may be done if they are houses, 

 hills, or trees ; or parallel lines (c, d, e) formed where practicable, and the main line 

 found by off-sets {f,g,h) from those collateral lines at such places as are suitable. A 

 third method, but one not always perfectly accurate, is to take a plan of the field or scene 

 of operations, and on this to set out the proposed line ; then by ascertaining its bearings 

 and distances relatively to the obstructions, it may be transferred from the paper to the 

 ground. In carrying straight lines through woods, lanterns have been used; but a much 

 more correct method is to elevate poles above the surface of the wood. 



3076. Continuous lines may always be made perfectly straight, however irregular the 

 surface, by following the same parallel as indicated by points of the compass; or by the 

 shadow of the operator during sunshine. If the needle does not move, or the shadow of 

 the spectator be always projected at the same angle to his course, the direction in which he 

 walks, in either case, must be straight. The mode of forming right lines in such cir- 

 cumstances being understood, the formation of right lined figures is merely a repetition of 

 the process, uniting each side by the required angle. 



3077. Curved lines on irregular surfaces are in general only to be laid down by the 

 previous establishment of straight lines ; first, leading straight lines, and next secondary 

 straight lines, which shall form skeletons to the curves. A second mode and on a large 

 scale, by much the most certain, is to find the leading points of the curves, by trian- 

 gles from a known base or known bases ; but as both modes are rare, they need not be 

 enlarged on. 



SuBSECT. 4. Of estimating Weight, Power, and Quantities. 



3078. Ascertaining the weight of objects is a part of agricultural knowledge, no less ne- 

 cessary than that of measuring their superficial or solid contents. In all ordinary cases, 

 as of grain, roots, bundles of straw, bushels of lime, &c. this is best done by a common 

 steelyard, suspended from a beam or a triangle of three posts. Cart or waggon loads are 

 weighed on those well-known platforms sunk in the ground at toll gates ; or sometimes by 

 steelyards on a very large scale. Cattle are weighed by machines of a particular kind, 

 which have been already described (2461. to 2463.). The weighing of cattle and grain 

 chiefly concerns the farmer, and is of consequence, in the first case, to ascertain the progress 

 of fattening animals,or the weight of those ready for the butcher ; and, in the second, to 

 determine the quantity of flour that may be produced from a given quantity of grain. 



3079. Estimating the quantity/ of power requisite to draw any implement or machine, is 

 performed by the intervention of the draught machine already described (2460. j, between 

 the power and the implement. It would not be diflScult to construct all agricultural 

 implements with a fixed draught machine and index, which would at all times, when they 

 were at work, shew the amount of power employed in moving them; but such an 

 arrangement would be of little use. 



3080. Estimating the quantity of work which servants and cattle ought to perform in a 

 given time, is an art that ought to be familiar to every agriculturist. In general no 

 absolute rule can be laid down, because so much depends on soils, roads, cattle, and other 

 circumstances; but in every particular case the rate or market price of labor per day 

 being given, and the quantity of -work ascertained which a man can fairly perform in a 

 certain time, a rate per yard, pole, or acre, or per solid quantity, if materials are to be 

 moved, can easily be determined on. A farmer should know by memory the number of 

 ridges or of single furrows, or bouts, which it requires to make an acre on every field of 

 his farm. This will aid him in every operation that requires to be performed on these 

 fields the quantity of manure, seed, ploughings, harrowings, hoeings, mowing, 

 reaping, raking, &c. ; as well as produce, whether of corn, hay, roots, or the number of 

 cattle or sheep that may be grazed there for any given time. 



3081. Road work, ditching, hedging, draining, trenching, ^c. ought to be subjected to 

 similar calculations, so as if possible to let out all work not performed with the master's 

 own men and cattle, by contract or quantity, instead of by time. As spade work is 

 nearly the same in most parts of the country, certain general rules have been laid down 

 by canal contractors and others, which, though seldom strictly followed up, yet it may be 

 useful to know. Thus in moving ground, as in digging a drain, or the foundations of a 

 building, if the soil is soft, and no other tool than the spade is necessary, a man will 

 throw up a cubic yard of 27 solid feet in an hour, or 10 cubic yards in a day. But if 

 picking or hacking be necessary, an additional man will be required ; and very strong 

 gravel will require two. The rates of a cubic yard, depending thus upon each cir- 

 cumstance, will be in the ratio of the arithmetical numbers 1, 2, 3. If, therefore, 

 the wages of a laborer be 2s. 6d. per day, the price of a yard will be 3rL for cutting 

 only, 6d. for cutting and hacking, and 9d. when two hackers are necessary. In sandy 

 ground, when wheeling is requisite, three men will be required to remove 30 cubic yards 

 in a day, to the distance of 20 yards, two filling and one wheeling ; but to remove the 



