534 SCIENCE OF AGRICULTURE. Pakt n. 



All we propose here is to direct the reader's attention to the most important points of the 

 art of surveying, and lay down the leading principles of Vcduing agricultural property. 



SuBSECT. 1. Measuring rdatwehj td ylgricti'/iut^- '.hi'^*J-' s ,ti. ^ , 



3295. The nieasuring of land^ or other objects, comprises three distinct operations ^ vf' 

 taking the dimensions of any tract or piece of ground, deliueafing or laying down tfie^ 

 same in a map or draught, and calculating the area or superficial contents. Tlie dim'efi" 

 sions on a small scale ai:e bust tidcen by rods of wood, but in all ordinary and extensi^^fe' 

 cases by a chain of iron, being less likely to contract or expand by changes of teinper- 

 aturfe than cord lines or tap'is. In measuring a simple figure, such as a square field, 

 nothing more is necessary than to take the length and breadth, which multiplied together 

 give the superficial area; but as few fields are square, or even right angled, it becomes 

 necessary to adopt some guiding line or form within the field, and from that line or 

 form to measure to the different angles, so as to be able, from the dimensions taken, either 

 to calculate the contents at once, or to lay down the form of the field on paper, according 

 to a certain scale, or proportion to its real size, and from that to take dimensions aiiq 

 calculate the contents. The simplest and most accurate mode of ascertaining the contents 

 of all irregular figures is by throwing them into triangles ; and this also is the most accu- 

 rate mode of measuring and protracting a whole landed estate, however large. In short, 

 a triangle is the form universally adopted, whether in surveying a single field, or a whole 

 kingdom. T<r find the contents of a triangle, every body knows that it is only necessary 

 to multiply half the pei-pendiculai- into the base. These two principles, properly vuider- 

 stood, form the; fo;ndiati.oii of measuring, protracting, and estimating the contents,. pf 

 territorial and all other surfaces. In surveying hilly lands, an allowance is made bp.tn 

 in protracting them> and calculating their contents, well known \Q surveyors, and noi 

 necessary to be entered into here. ,. , .;, ., ,, ;. ., , 



3296. Ill mettsvring so/ul bodies, the rule is to " find the area of one end, and multiply 

 that by the length." This rule is of universal application, whether to land, as in e%-^ 

 cavating or removing protuberances ; to ricks of corn ; heaps of dung ; timber j or wat^r. 

 The area of one -end, or of one surface, whether the end, side, top, or bottom, is found 

 exactly on the samie principles as in ascertaining the superficial contents of land ; and, i^' 

 the figure diminishes in the course of its length, as the tpp ^f .jE^,^^,oiC i^hgj tpj^gij?, 0^ a 

 tree, the mean length or half is taken as a multiplier. ,,(..[,,,, i., ,.,i ,. ,-. ,,,^ ,,h. i ,^ 



3297. Measuring objects by the eye, though a mode that can never be depended on a^ 

 the foundation for any important calculation or transaction, yet should be constantly 

 practised by young men, for the sake of gaining habits of attention, and acquiring ideals 

 as to number and quantity at first sight. Tlie principle on which this sort of eye measure- 

 ment is acquired, is that of ascertaining the actual dimension of some near object, and 

 applying it as a measure to all the others seen beyond it. Thus, if a man is seen standing 

 by a post or a tree at a distance, taking the height of the man at five and a half or six 

 feet ; apply the figure of the man to the tree, and find how many applications will reacli 

 its top ; that number multiplied by the ordinary height of a man, will of course be a 

 near approximation to its height. Again, supposing this tree one in a row or avenue, 

 then to estimate the length of the avenue, measure the third or fourth tree by the man, and 

 measure by the same means the distance of that tree from the first, then state the question 

 thus : As the difference, between the height of the first and fourth tree is to the horizontal 

 distance between there; sd is the difference between the first and last tree of the avenue, 

 to the length of the avenue. In this way, the length and breadth of a field may be 

 estimated by observing- the (height of the hedge at the nearest side, and the apparent heigljt 

 at the farthest points. The breadth of ridges and tlieir number, teams at work, or cattle 

 grazing, or accidental passengers, are all objects of known dimensions, which may be 

 made use of in this way of egfeiiiKitJeg the cojtit^r\tsi qf^land^, , In regard to housesj, the 

 doors, and windows, and size of bricks, stones, boards, tiles, &c.iare obvious anci certain 

 guides. - ^ ^< 



3298. The recollection of surfaces and of country is 2i matter of eoniderabk interest to 

 every one, but especially to the agriculturist. The most effectual mode of impressing 

 scenery on the memory is by the study and practice of sketching landscape. In addition 

 to this, it will be useful to pay attention to the natural surface and productions, as kind of 

 tree or crop, hills, valleys, flats, lakes, rills, &c. ; also to the distant scenery, as whether 

 flat, hilly, cultivated, was^, woody, or watery ; what processes are going on; what the 

 style of houses, dress, &c. . ''Sgvmg- atten ded to- these details, the next and the most im- 

 portant aid to the memoiy is tD| recollect what portion of country already known to us it 

 most resembles. - t' .>f ^ - 



3299. In endeavouring to ree^ectihe surface ^nd objects composing an entire estate, some 

 leading central object, as the house, should be fixed on, and the bearings of other objects 

 relative to it ascertained in idea. Then, either by going over the estate, or by a favourable 

 position on the house-top or some o(her'*eixiihcnccV the oittline' tf thO'fieldiBj^or- o^ 



