74 A MANUAL FOR NORTHERN WOODSMEN 
revolved on its axis; (3) the axis of the telescope bubble 
to be parallel to the line of sight, thus enabling the instru¬ 
ment to be used as a level; (4) the vernier on the vertical 
circle to be so adjusted as to give the true altitude of the 
line of sight. These results may be secured as follows: 
a. To adjust the plate levels so that each is in a plane 
The Transit 
