406 A. M. BATEMAX MILITARY AND GEOLOGIC MAPPIXG 



table is the most satisfactory instrument and the geologist is partic-ularly 

 adapted to render such instruction. 



For the purpose of instructing artillery students and officer candidates 

 of the Eeserve Officers' Training Camp and members of the Students' 

 Auxiliary Training Camp at Yale University in these phases of the 

 work, a simple plane-table equipment and methods were used, which, for 

 the instruction of large numbers, yielded more accurate and efficient re- 

 sults than the methods generally employed throughout the training camps 

 of the country. 



These features are here presented in the hope that they may be of use 

 in future military training, and particularly that they may be of value 

 for the training and use of geologists in their fieldwork. 



Equipmext 



COST 



The plane-table and the alidade were designed for simplicity and 

 cheapness, the materials being obtained and made locally at a total cost 

 of $1.53 each for a lot of 160. A single outfit could be obtained from a 

 country village in a few hours, and thus be available for a field geologist 

 needing one on short notice. For instructional purposes their cheapness 

 allows large numbers to be obtained at a small cost, thus enaliling better 

 individual instruction to be given. 



PLAXE-TABLE 



The tripod is an ordinary, cheap, wooden camera tripod with sliding 

 legs in two parts (see figure 1). The legs are permanently fastened to the 

 head, insuring greater stability than with those types which are detached 

 from the head. The sliding legs shown in figure 1 also tend toward greater 

 stabihty than those which are taken down by folding back on themselves, 

 as in the more expensive type of camera tripods. While they are not as 

 stable as solid legs, they have the advantage of lightness and of being 

 shortened to one-half their total length. 



The camera tripod is often objected to because of its instability, and it 

 is true that many types are too unsteady for plane-table work. However, 

 the one described here was found in practice to be so steady that points 

 could be accurately located by the precise three-point methods. 



The board is of pine, 15 inches square, with inset ends to prevent 

 warping. A brass nut inserted in the lower side enables the board to be 

 screwed to the tripod head, and the same screw is used to clamp or un- 

 clamp the board. 



