2 PRELIMINARY MEASUREMENTS 



Note. — In practically all engineering and mensuration work the distance 

 between two points is expressed in terms of horizontal distance. Therefore in 

 pacing across broken country the horizontal distance must be secured. Where 

 the topography is rolling this may be accomplished by slightly lengthening 

 the step, but where the slopes are steep resort should be made to one of the 

 following expedients: 



a. Take extra steps to secure the unit pace. 



b. With a Jacob staff or a stick lay off the pace horizontally on the ground. 



c. Estimate the distances in terms of some unit of distance, i.e., pace 

 rod, or chain. 



. When you can pace the original course satisfactorily, lay olT a dis- 

 tance of a quarter of a mile in some other direction by means of 

 pacing and a hand compass. During the actual process of pacing 

 make a rough plat to a suitable scale of the physical features such 

 as woods, trails, creeks, fences, etc., of the country you cross and 

 note on the plat the distance in feet of each from the starting point. 

 Draw the plat on Form 1 of the Field Note Book. 

 4. Check the accuracy of your pacing. With the aid of another mem- 

 ber of the class go over the course covered in 3 above with compass 

 and steel tape and note on the plat the exact measured distances 

 from the starting point to each of the physical features indicated. 



D. References. — Consult table of units of measure in Appendi.x. 



PROBLEM 2. (Field) The Determination of the Diameters of Standing 

 Trees. 

 Explanation. — The object of this exercise is to give practice in estimating 

 the diameters of trees by eye, to show the use of different types of in- 

 struments, and to compare the efficiency of the different methods in use 



Directions. 



A. Parties. — Parties will consist of two men each. The men should alter- 



nate in the use of the instruments and in tallying results. 



B. Equipynent Required per Party. 

 1 pair tree calipers. 



1 Biltmore stick. 



1 diameter tape. 



1 dendrometer. 



1 field note book supplied with Form 1. 



C. Method of Procedure. 



1. Obtain the diameters at breast height (D.B.H., 4.5 feet above ground) 

 in inches and tenths, of at least 20 trees with each of the above 

 instruments after first estimating the diameter by eye. The 

 average diameter should always be taken . This can best be obtained 

 by taking two measurements at right angles to each other. 

 In using the instruments note the following: 



