16 



a complete survey is quite out of the question, aud sample 

 plots should be surveyed, if there are no volume-tables avail- 

 able to furnish the requisite data and dispense with the 

 necessity of any measurements. 



III. IN A CERTAIN SENSE, ALSO THE NATURE OP THE GROUND. 



On gentle slopes the whole crop can be easily surveyed, 

 but on steep or rough , rocky hill-sides, a complete survey 

 would be difficult as well as expensive, and the adoption 

 of sample plots would be justifiable. 



5. Selection and Demarcation of Sample Plots. 



It is hardly necessary to say that the sample plots should be as 

 nearly as practicable a true average sample of the entire crop. 

 Hence, before selecting it, the surveyor should go over the whole 

 crop, so that its average character may become clearly impressed 

 on his mind. 



The following rules may be laid down for observance : 



I. No sample plot should ever be selected on the edge of 

 the crop, for a true average will seldom be found there. 

 II. On slopes presenting a wide range of elevation, or in 

 crops offering a variety of aspects and soils, several 

 sample plots judiciously distributed, should be selected. 

 III. The form of the sample plot should be a long rectangle. 

 IV. The boundary of the sample plot should be clearly marked 

 by blazing the trees immediately outside, or by 

 splashing them with whitewash. 

 V. The aggregate area of the sample plots should be from 



3 to 5 per cent, at least of the total area of the crop. 

 VI. In mature crops, no sample plot should be less than 

 1 acre in extent, and <he minimum area should, as 

 a rule, be 2 3 acrejs. In young uniform crops, con- 

 taining a large number of stems, or even ^ acre 

 may suffice. 



VII. In crops of large extent, several plots of 12 acres each 

 are preferable to a single large plot. 



4. Enumeration Survey of the Crop. 



Bi-fore arry attempt can be made to calculate the quantity of 

 material in a crop, we must find out the number and respective 



