ENGINEERS' PRECISE LEVEL 



Made exclusively by the Rausrh & I.omb Optical Co. 



HIS instrument might otherwise be known as a precise 

 dumpy level. The design adheres generally to the 

 dumpy model, but any leveling instrument provided 

 with a verticalcontrol, tosupersedethelevelingscrews 

 as a means of securing an accurate setting of the 

 bubble at the moment of observation, may be known 

 as precise. 



In the Y-level the collimated sight-line is at the 

 basis of adjustments. In the dumpy type, adjust- 

 ments have usually been referred to the vertical axis. In the E. P. L. 

 either plan may be pursued, preferably the first, buttheadjustment 

 for parallelism in any event must be conducted over the pegs. 



The choice of instrument and method of adjustment depend 

 upon whether one wishes to test adjustments frequently through 

 the collars (which are in themselves the very necessity for frequent 

 tests) or to take a little more time in the process of adjustment, in 

 favor of greater stability of construction and the consequent greater 

 permanency of the adjustment so made. 



