STANDARD COMPASS. 11 



and to inch scales on two sides. One of these scales is 

 Forest Atlas standard of 1 inch to 1 mile, and is 

 divided into eighths, each of which represents 10 chains. 

 The other scale is decimal. The base supports two 

 levels, D, set at right angles to each other, each being 

 adjustable by means of small screws and a center point 

 on which they rock. 



The clamp E is a milled nut which operates to lift 

 the needle from the center pin when the compass is not 

 in use. It works so easily on a screw that the azimuth 

 of the instrument need not be disturbed when the needle 

 is undamped or clamped. The thread is riveted on the 

 top so that the nut will not come off and be lost. 



The needle F is of blue steel and is provided on its 

 south end with a small brass weight, which may be 

 pushed toward or away from the center if it becomes 

 necessary to make the needle hang horizontal and 

 counteract the magnetic dip in any locality. Of course 

 the needle should be removed from the center pivot 

 when this is done. The base dial is reenforced at H to 

 hold the center pivot more securely. It is engraved 

 to show (1) the cardinals, (2) a half circle of degrees 

 for the clinometer, and (3) 70 of variation, including 

 east and west. The ring dial / is graduated to degrees 

 reading from zero , from north and south, to 90 at 

 east and west. It carriers a vernier, J, which reads 

 against the variation graduation on the base dial. The 

 cover is of heavy plate glass and is held in place by a 

 graduated and slotted rim, K, which also revolves in 

 azimuth. 



The clinometer consists of a weighted pendulum, L, 

 which hangs on th,e center pivots and is provided with 



