STANDARD COMPASS. 9 



The grademeter; 



The Locke hand level; and 



The Abney reflecting level, which is provided with a 

 vertical arc, graduated either to per cent, degrees, or 

 ratio of slope, according to the purpose for which it is 

 used. 



The unit of land measure is the standard surveyor's 

 chain of 66 feet. For some classes of work steel band 

 chains or steel tapes are found more convenient and 

 economical, because they are lighter and greater 

 lengths can be dragged over the ground, thus effecting 

 a saving i.n pinning and tallying. Tapes are usually 

 graduated in feet, and when they are used it is necessary 

 to reduce the measurements to standard chains, in 

 order that they may conform with the official land sur- 

 veys. In some regions the best means for determining 

 distances are the stadia transit and rod. These in- 

 struments are used by specially trained men, and are 

 therefore not described here. 



FOREST SERVICE STANDARD COMPASS. 



Figure 1 shows the surveying compass which has 

 been adopted by the Forest Service for the use of field 

 men in making forest surveys and maps. Very accu- 

 rate work can be done with this instrument if properly 

 used, and for this reason requisitions for transits should 

 not be made unless there is a special need for using a 

 still higher grade instrument. The principal features 

 of this standard compass are as follows: 



The sights are very tall, and therefore admit of Use 

 on steep hillsides or in taking observations on Polaris. 

 The hair sight may be repaired easily by threading 

 through the holes at A and B. If after long use the 



