80 



A MANUAL FOR NORTHERN WOODSMEN 



on distances from one quarter to one third of a mile, giving 

 results which are accurate to within a few feet. 



Example and Reduction of Readings. 1' on rod cut off 

 at distance of 100'. In computation, correction made for 

 1' instrumental constant. True horizontal distance and 

 difference of elevation between points both worked out. 

 Height of instrument over station obtained at each setting 

 and center hair for vertical angle read at same height on 

 rod. 



Computation. First shot, with v. a. of 1 30', rod reading 2.00'. 

 Add .01' for instrument constant, making 2.01', for corrected rod 

 reading. From table the horizontal distance fof 1' rod reading is 

 found to be 99.93' the difference of elevation 2.62'. For 2.01' rod 

 reading the elements are 99.93 X 2.01 and 2.62 X 2.01 or 200.86' 

 and 5.27', as above. 



Second shot, 1.80 + .01, = 1.81, corrected rod reading. 



For v. a. 4 10' and rod reading 1', horizontal distance 99.47 

 and diff. elev. 7.25 are found in the tables. 99.47 X 1.81 and 

 7.25 X 1.81 = 179.84 and 13.12. 



Similarly for succeeding shots 



4. USES OF THE TRANSIT 



To Take the Bearing of a Line. Set up over the first 

 point, level the instrument, free the needle, and turn the 

 telescope toward the other point. Read the bearing in the 

 same way as with a compass. 



When set up on the forward one of two points, exactly 

 the same bearing may be read as if the instrument were 



