Tory Emoli groat or accuracy results from this practice than 

 can be obtained by tailing notes, hcrrovor voluminous and at- 

 tenptins 'to put in the contours in the office where the e::- 

 act appearance of the to . ography io forgotten or at tho very 

 leact natoriall3r d inane c. in the nenorjr, 



Y o r L' i c a 1 o nt i o 1 , The aneroid sjrstem of vertical 

 control is adaittodl:^ insatisfactory* The method noct need 

 to insure as much accnracy as can "be obtained, has "been that 

 of having a oanp aneroid which is read at intervals, cay two 

 houi'G, thron:>hout the day "by which to chocl: the field aner- 

 oids. This involves a great oizjendituro of time and labor, 

 since in oi'der to "ose tho net hod wo rmst , 



1. Ourve tho readings of the camp "barometer, 



8. Drav; curvos hamonizin^ with that of tho camp "barometer 

 for the starting and returning readings of the field "barcm- 

 otor. 



ZM Redrew tho field naps, correcting the contours in ac- 

 cordance wit /i the "baroiaotor's curves, 



I "boliove the o:rponse of this method to "be warrant- 

 ed only for abnormally creat variations, since the jarring 

 inseparable from car^i:.!^ 1 it in the field cannot oe prevent- 

 ed from producing fluctuations in an instrument so delicate 

 as tho "barometer, greater in amount than those produced by 

 ordinary atmospheric differences, 



TThere U.3.G-.S. topocraphic shoots are available for 

 an area I believe o-ual accuracy can be obtained with less 

 expense b'. the following method: 



82 



