PRKLIMINARY SURVF.V 33 



In surveyed districts, these preliminary surveys usually sampled 

 every section. In other cases such preliminary surveys establish 

 systems of base lines or "control lines" from which caliper crews 

 work out in both directions and cover the country in a regular order, 

 and actually measure the timber on a certain per cent of the total 

 property, and map and describe the soil topography, forest types, 

 etc. Generally these preliminary surveys cost less than 3 cents per 

 acre including office work of compilation and map work ; they are 

 necessary and useful. They merely sample by covering usually less 

 than 5 per cent of the area ; they do not leave a permanent survey or 

 subdivision on the ground ; they are not easily controlled or checked ; 

 any verification requires a repetition of a large part of the work, and 

 even then it is usually impossible to decide the merit of the case, for 

 the inspection rarely follows the same line followed by the crew in 

 the first place. Leaving no permanent survey marks, a later repeti- 

 tion, verification or correction is impossible, imless the matter of 

 land survey is specially attended to. Nevertheless the results are 

 useful, and often surprisingly accurate. The maps and descriptions 

 alone justify the effort. Where the strip method and caliper crew 

 are employed, the results are accurate for the samples actually 

 measured, but they are inference for the rest. In this way the 

 estimate of timber, for instance, may be fairly good as an average 

 for a large area (township, stream — valley) but may not apply at 

 all to a particular forty-acre tract. But in actual operations, log- 

 ging, etc., it is usually desirable to know just what the forest is on 

 a given forty and even the lumbermen have found it necessary, 

 therefore, to amplify the information by a detailed examination, an 

 estimate by forties. 



With these limitations, the Preliminary Survey is useful ; it 

 may quite suffice for many years in cases of remote properties with 

 little or no market; it is quite sufficient for protective forests, "timber- 

 line" country, etc. On properties or parts of properties with good 

 forest, with market for timber, and consequent development, the 

 work of utilization with its improvements, of protection and silvi- 

 culture, soon calls for more accurate and more detailed information. 

 And especially do these lines of work demand that any information 

 apply to a definite location, to an area clearly marked on the ground 

 ,so that it can be found without repeating surveys, and to apply to 



