March, 1931] ' LAND SURVEY OF DURHAM ' 23 



is done, the more accurate methods are necessary, both as to base map 

 and field work. 



In the absence of an accurate topographic map a plane table survey 

 of the roads would be necessary. 



The financing of such a survey can easily be arranged if the towns 

 thiidv the results worth while. 



To those who are accustomed to surveying done by a crew of six men 

 or so. using either a transit or a staff head compass for direction and a 

 tape or chain for distance, these methods seem haphazard. They are. 

 If property lines are to be run out and corners set on the ground, an 

 error of 20 feet in location is very important. If. on the other hand, 

 the aim is to draw a map on a scale such as was used in Durham, where 

 a pen line is ten feet wide and an error of less than 20 feet is hard to 

 see, such accurate work is unnecessary and rather extravagant. Such 

 a crew could map the outside lines of a property for a minimum of 

 fifty cents an acre, while the pacer can make the outside lines, and 

 the interior as well, for 7c. The more accurate methods should be 

 used where lines are to be established. The transit is out of place in 

 most woods work, for it requires too much axe work and is too slow. 

 The compass, either on a staff or tripod, is commonly used with a chain 

 or tape in extensive cruising where long strips are run and only the 

 ends located on known base lines. This method is applicable where 

 rough topography and large tracts make pacing errors large, although 

 even here a tw^o man crew does about what one man could do alone, 

 pacing, and. while the land along the strip run is mapped more 

 accurately, that between strips is often sketched in later. This can be 

 corrected only by increasing the cost. This type has the decided 

 advantage of not requiring labor as skilled as the paced survey, to 

 obtain the same degree of accuracy. The compass and tape, or plane 

 table and tape are excellent for making base maps where these are 

 necessary, although pacing to a traverse board, if done carefully, is 

 faster, much less expensive and nearly as accurate, from a mapping 

 standpoint.* 



Certainly pacing has much in its favor for mapping the small, 

 irregularly shaped lots common in farming communities of southern 

 New Hampshire when compared to the more cumbersome, slower, more 

 expensive, though more accurate, methods commonly used by 

 surveyors. 



*A base map made in this way for about 5000 acres in the town of Fremont, 

 N. H., closed within 2 chains (132 feet) wherever checked against itself — 

 an error which is insignificant when distributed over the whole area. 



