The Gradienter 



Perhaps the strongest argument advanced against the stadia as 

 in favor of the gradienter screw is the fact that all gradienter 

 observations are taken with the central horizontal cross wire and 

 immediately reduced to the center of the instrument, whereas the 

 stadia sights are removed from the optical axis into the zones where 

 aberrations of greater or less extent are possible. While the instru- 

 mental constant does not enter into the calculations, they are, 

 however, no less complicated when inclined observations are made 

 with the vertical rod. 



Fig. 6g 



Its invention, as an attachment to the Theodolite for gradient 

 and telemeter work, is usually attributed to Prof. S. Stampfer, of 

 Vienna, in the early seventies of the last century, but the micrometer 

 principle certainly was not new at that date. 



Considering the variety of useful purposes to which it may be 

 applied, it has not yet achieved the popularity it merits. It can be 

 attached to either the vertical or hori/ontal tangent movements, can 



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