METHODS OF MAP MAKING 129 



D. Western Topography. Use of the Clinometer. 

 The above described methods grew up in the East among 

 varied conditions of topography and value. Brush that 

 interferes with sighting is widely prevalent, and another 

 determining factor is the general employment of horse 

 logging, a style of operation for which close regulation of 

 grades is not essential. Conditions in the West are fre- 

 quently different from the above, in respect to one or 

 more particulars. 



The aneroid barometer has not on that account yielded 

 its place entirely. Particularly in Western Washington 

 and Oregon does it still hold the field, because of the dense 

 brush widely encountered, which makes almost impossible 

 the clear sighting necessary for the employment of any 

 other height-determining instrument. On the contrary, 

 the temptation is to rely on the aneroid for work that it 

 should not be called upon to do. Where, as is the case 

 here, railroads are employed for nearly all mam transpor- 

 tation, heights with a reliable basis are essential if a 

 map is to be widely serviceable. Frequently the ground 

 lies in such a way that the routes of future railroad de- 

 velopment are evident. Levels run along these routes,, 

 with aneroid work for the rest, is then the natural treat- 

 ment. Just this method has been employed in numerous 

 cases. 



Such logical and adequate treatment is not always 

 possible, however, nor is it always permissible under the 

 restrictions of the work in hand. A variety of methods is 

 in fact employed, especially for the control work. As 

 for the detail, the fact remains that when points in eleva- 

 tion have been reliably determined at distances not more 

 than from one to two miles apart, good aneroids intelli- 

 gently used will give topography sufficiently accurate for 

 general purposes, while here as elsewhere their use saves 

 expense by permitting the topographic and estimating 

 work to be done together. Complaints of the results of 

 aneroid work frequently arise from unskilled use and from 

 employment of instruments of inferior character. The 

 quality of instruments obtainable at moderate cost has 

 within a very few years greatly improved. It is not to be 



