4i8 



Report S.A.A. Advancement of Science. 



Note : The writer prefers to do the calculations in a foolscap 

 book, square sectional paper, rather than on loose sheets of paper. 



The date and reference to page and number of field book should 

 always precede the calculations. 



X is a symbol, meaning " the angle of direction of." 



X 930 — 929 and X 929 — 930 are both copied down from final 

 calculation for 929, the two angles differing by 180 degs. By 

 adding the right angle to the one, and subtracting the left angle from 

 the other the new angle of direction is obtained in two ways, differing 

 by 180 degs. The check on taking out the angles from the field 

 book is that they add to approximately 360 degs. allowing for the 

 errors in reading. The mean is taken out to the nearest 10 sees., the 

 extent to which the logarithmic tables are used. 



Dips are worked out first; an angle of dip of less than i deg. is 

 negligible for cosine. Elevations are carried out at once by bringing 

 forward reduced level of starting point. If it has been necessary to 

 work out horizontal distance,- then logarithm so obtained is brought 



