412 j. F. KEMP — GEOLOGICAL BOOK-KEEPING 



coming so numerous and widely distributed they can be taken as the 

 basis of work in all parts of the country. They will therefore be as- 

 sumed as the foundation of the system, although it will apply to any 

 map. The subject maybe best set forth under two heads: The field 

 map and note book, and The compilation book. 



The Field Map and Note Book 



The usual methods of employing maps and locating observations, so 

 far as the writer can learn, are the following: The note book being ruled 

 in squares, a suitably sized piece of the map is pasted upon a page so 

 that locations can be made, as in atlases, by a row of letters across the 

 top and numbers down the sides. Between intersecting horizontal and 

 vertical lines any special point may be noted. With numerous and 

 closely set observations this system does not admit of great accuracy, 

 and it is difficult to locate oneself accurately when away from the sides 

 and top of the sheet. 



According to another method, the observer, when setting out from a 

 base or center of operations, draws a line on the map showing his course, 

 and upon this marks consecutively numbered stations where specimens 

 or notes are taken. This is very accurate, but in detailed work it leads 

 to a confusing multiplicity of lines, and does not work up to systematic 

 compilation as an end-result. 



In the method here set forth the usual topographic sheet is lightly 

 ruled with waterproof india ink in squares of a mile or two miles on a 

 side according as the scale is -g-j-Voo" or txsVoo"- This gives useful areas 

 in estimating size and distance. Each second vertical and horizontal 

 line is drawn double, so that the double lines enclose four squares of 

 single lines. At the intersection of the single lines numbers are written, 

 also in waterproof india ink, and in this invariable order : 



Beginning in the upper left-hand corner the numbers 1, 2, 3, and so 

 on to 7, are written at the intersection of the single lines, as shown in 

 figure 1, so far as it goes across. Below 1, 11 is put on the next row, 

 and so on across, 12 running under 2, 13 under 3, etcetera. The next 

 row begins with 21, and is all in the twenties, and so on to 81 and other 

 eighties along the bottom row. This makes an invariable decimal system. 



The four squares around each number are now themselves numbered 

 in an invariable order, as shown in figure 1, but these numbers are not 

 placed on the map, since it requires no effort to recall that the northwest 

 square is 1, the northeast 2, the southwest 3, and the southeast 4. We 

 thus have a system by which each square has its own number, as 1, 2 ; 

 43.3; 61.4, etcetera. Each square is now subdivided into ninths, and 

 the ninths are enumerated, as shown in square 12.1 of figure 1. They 

 are not put down on the map, however, as it is easy to estimate them. 



