SURVEYING PRACTICE 19 



should be so s'paced that one foot on the rod will be cut off 

 when it is held at a distance of 66 feet, or, if the wires are 

 fixed, the rod may be graduated to correspond. For occa- 

 sional use in land surveying, the rod may best be made 

 of painted canvas, which, in case of need, may be tacked 

 on any pole that comes to hand. 



The Stadia Hand Level is a simpler form of the instru- 

 ment, adapted to the measurement of the width of gorges 

 or ponds. It is readily carried in the pack, and, when in 

 use, may be held in the hand or mounted on a staff. The 

 ready range of this instrument is 200-300 feet. 



7. UNITS OF DISTANCE AND AREA 



7.92 inches = 1 link. 



25 links = 1 rod. 



100 links = 66 feet = 1 chain. 



320 rods = 80 chains = 1 mile. 



160 square rods = 10 square chains = 1 acre. 



640 acres = 1 square mile or section. 



The vara, a measure of Spanish origin, prevails in Cali- 

 fornia and in Texas. The California vara is 33 inches. 

 The Texas vara is 33 J inches, and 5645.376 square varas 

 make one acre. 



In Louisiana and the Province of Quebec, the arpent, 

 an old French unit, is the measure of areas. This is .8449 

 acre. 



The hectare = 10,000 square meters (meter = 39.37 

 inches) or 2.47 acres. This is also a French measure. 



SECTION IV 

 SURVEYING PRACTICE 



The starting- point of a survey is generally settled for a 

 surveyor by outside controlling circumstances. When this 

 is recognized, the next thing to do may be to find out what 

 course to run by an observation for the true meridian, or 

 by finding the bearing of an old line. With the starting 

 point and course determined, the method of procedure is 

 about as follows. 



