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. 
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 
