LAND SURVEYING. 



LAITO Measuring is the art by which we ascertain tlie super- 

 ficial content of any tract of ground. 



There are Yarious methods of obtaining the measurement, 

 pome of them requiring familiar acquaintance with mathematics, 

 whilst others need nothing beyond a knowledge of the simplest 

 principles of mensuration. As the present work addresses itself 

 entirely to practical men, we shall confine our remarks to the 

 popular method ordinarily employed. 



Land is commonly measured with what is called Outlier's 

 chain. This chain is divided into 100 links, and at the end of 

 every ten links a piece of brass is fixed, with notches denoting 

 the number of tens, so that the number of links may be readily 

 ascertained. The English chain is 22 yards or 66 feet in length, 

 and each link 7.92 inches ; the Scotch chain is 74.1196 feet long, 

 each link being 8.894352 inches. Both chains are divided into 

 100 links. The English, or Imperial measure, is now the only 

 legal standard in the United Kingdom. 



In taking measurements in the field, the various distances are 

 set down in links, which are afterwards reduced to acres, roods, 

 poles, <fcc. The field requisites for a land-measurer are the 

 chain just mentioned, a bundle of arrows, a cross-staff, and a 

 number of signals. The arrows are usually ten in number, and 

 two feet in length, each has a piece of red cloth affixed to the 

 head, by which it is easily distinguishable at a considerable dis- 

 tance when stuck in the ground. The use of the arrows is to 

 indicate the number of chains in any line of the survey. The 

 cross-staff is a pole 10 links long, shod at one end with iron, and 

 pointed, that it may be thrust into the earth as occasion requires. 

 A small block of wood about 6 inches square, having grooves cut 

 round its margin at right angles to each other, is fitted on the 

 pole, and slides up and down according to the height of the eye ; 

 its use is for obtaining a perpendicular from the base line of any 

 triangle to the angular point. The signals are more or less 

 numerous, according to the extent of the field or tract to be sur- 

 veyed; their use is to mark definitely the various points and 

 bearings ; they are usually slight poles, from six to eight feet in 

 length, with a small red flag attached to each. 



Land surveying is divided into three distinct operations. 

 L The actual measurements in the field. . IT. The plotting, or 

 laying down on paper all the lines and angles of the-.field, accord- 



