MEASUREMENT OF DISTANCE 



15 



serves good men to carry it on, men who will get down to 

 the ground and take all needed pains in marking, level- 

 ing, and alignment. They should be brisk men, moving 

 quickly and doing their work in a prompt and business- 

 like manner. Much, too, depends on system, on tally- 

 ing, passing pins, etc., from habit and in regular order. 

 Some men never will make good chainmen because they 

 will not take sufficient pains about details. A few in their 

 strict attention to these are liable to make gross blunders. 

 The man in general charge of surveying work must give 

 careful attention to this part of the business. Chainmen 

 must be trained in good methods and watched till they 

 are perfectly trustworthy, while careful consideration must 

 be given to sources of error and to possible improvements 

 in method. 



5. MEASURING INACCESSIBLE LINES 



Ponds, bogs, and bluffs, over which it is impossible to 

 chain, are met in the practice of nearly every surveyor, and 

 quick and accurate measurement across them constitutes 

 one of the problems which he has frequently to solve. Each 

 problem of that kind has to be solved in the field according 

 to the ground and circumstances. The methods commonly 

 employed in such cases are as follows: 



1. Offset. Frequently a short offset squarely to left or 

 right will clear the obstacle. 



FIG. A 



2. Method by 45 Angle. (A) With the compass at a, 

 set a stake in the line at b across the obstruction, and, 

 turning off an angle of 45, set another stake on that range 



