MISCELLANEOUS WORK 201 



This figure must be deducted from the area of the 



parallelogram — viz., 178,000 square yards, which leaves 

 117,655 square yards, or 24-308 acres. 



I have given these figures in yards as a hnk is too 

 small a unit for such a small plan as the above, but for 

 actual measuring the chain of 22 yards, or 100 links, is 

 more convenient. A tape marked in hnks is generally 

 used, being lighter and handier than a steel chain. A 

 chain is made of 100 hnks, each 7-92 inches long (792 

 inches in one chain, divided b}- 100=7-92). It is -^ of 

 a mile, J^^ of a furlong ; a square chain is a ^ig^ part of an 

 acre. Ten square chains, therefore, make 1 acre, and 

 the computation of areas is thus made simple. The hnks 

 being decimal parts of a chain, the measurements may 

 be written 5-50 chains, or 75 hnks as -75 of a chain. 



All calculations are then made by decimal arithmetic. 



In using the chain or tape on a line previously poled 

 out, the surveyor stands at the starting-point of the line, 

 holding one end of the chain. His assistant, holding the 

 other end, and carrying ten pins or arrows, walks along 

 the line until reaching the full extent of the chain, which 

 he stretches tight and straight. At this point he places 

 a pin upright in the ground in a hne between the points 

 to be measured. He is guided in this by signs from the 

 surveyor. He then moves on to the end of the next 

 chain length, where he again puts in a pin. When this 

 is properly placed, the surveyor picks up the first pin and 

 moves on to the next. 



This continues until the ten pins have been used and 

 picked up by the surveyor. The chain is left lying 



