The telescope will now occupy a position in an inclined plane, 

 making a slope of 1.65J& with the hori/on, and will cut any 

 position in the field, in the general direction of the telescope, in 

 this proportion with respect to the peg over which the instrument 

 is located. In other words, the line of sight occupies a position 

 parallel to the grade which is to be established. The H.I. 

 is a constant for that particular set-up. Let it be assumed that this 

 is 4.857 and that a down-grade is being run. 



The rod may be held at any point on the grade line without 

 regard to its distance from the instrument. 



Suppose the tiist reading to he 

 H. 1. 



Kill, 



Again : 



The H. I. being ... 4.857 



Suppose the second reading to be 2.715 



Cut, 2.142 



