SCIENCE OF AGRICULTURE. Part II. 



may be found by the usu of poles ■ few feet higher than the elevation of the obstruc- 

 tions, the director being placed on a step-ladder, or other elevation, at one end. Where 

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

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

 houses, hills, or trees; or parallel lines ( ( -, d, <•) formed where practicable, and the main 

 line found by off-sets ( f a, h) from those collateral lines at such places as are suitable. 

 A third method, bul one nol 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 ils 

 bearings and distances relatively to the obstructions, it may he 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. 



3317. Continuous Una 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 ease, must be straight. The mode of forming right lines in such 

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

 of the process, uniting each side by the required angle. 



3318. Curved Hues 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 

 stale, 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. Estimating Weight, Power, and Quantities 



3319. Ascertaining the tveight of objects is a part of agricultural knowledge, no less 

 necessary 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 (2566. to 2568.). The weigh- 

 ing 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. 



3320. Estimating the quantity of power requisite to draw any implement or machine is 

 performed by the intervention of the draught machine already described (2563.), between 

 the power and the implement. It would not be difficult 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 woidd be of little use. 



3321. 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 labour 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 

 ot 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 in estimating the produce, whether corn, hay, roots, or the num- 

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



3322. Road work, ditching, hedging, draining, trenching, c^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, it may 

 be useful to know. Thus in moving ground, as in digging a drain or the found- 

 ations 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 circumstance, will be in the ratio of the arithmetical numbers 1, 2, 3. If, there- 

 fore, the wages of a labourer be 2s. t></. per day, the price of a yard will be 3d- for 



