CANADIAN FORESTRY ASSOCIATION 39 



indicates the positions of ridges and streams, the shape and steepness of slopes, 

 the areas of valleys and lakes, and the grade of roads that it may be necessary to 

 build. 



METHOD OF COLLECTING DATA. 



One of the methods used to secure the necessary data for such a map is 

 somewhat as follows: 



From points of known elevation, along railways, etc., a line of levels is run to the 

 ponds and other suitable places well distributed throughout the township to be 

 surveyed. From the places whose heights above sea level are thus determined, it 

 is customary to work out with aneroid barometers, which give the approximate 

 elevations with sufficient accuracy for all kinds of woods work. In determining 

 the grades of roads which it may be desirable to build it is found that an Abney 

 clinometer is much lighter, quicker and almost as serviceable as a land level. 

 Usually the land is blocked out into mile squares, and easily found marks are 

 made every quarter of a mile. These marks serve as starting points for the exam- 

 ination of the interior of any given " forty" and enable the cruisers to locate them- 

 selves quite accurately on a line by pacing. With practice, measurement by 

 pacing can be made much more accurately than would be supposed. Steps 

 taken to get round obstacles are not counted, and on strong slopes discount is made. 

 On very steep ground, indeed, steps taken are not a guide to distance, and judg- 

 ment has to be resorted to in order to fill in the count. The count tells us when a 

 line is approached, and enables us to pick it up with certainty, though it may be 

 blind. By this means locations may be made with considerable accuracy along 

 the whole line. Having traversed the lines of a lot, noted the crossings of brooks 

 and divides, taken the heights of essential points and noted and sketched whatever 

 topography can be seen, we may then start from the middle of one side to run a line 

 across the lot. In doing so, it is best to use a pocket compass with a needle less 

 than two inches in length, because a man climbing over the debris left by cutting or 

 shoving his way, head down, through dense thickets of young fir, etc., will lose his 

 direction in the course of a few rods. Now, if he has a compass in hand he will 

 stop and look at it, but he would do so less often if he had to set a staff, level a three 

 inch compass with folding sights and wait for the needle to come to a stand. From 

 what has been said it is evident that a pedometer is of little use in this kind of 

 work. For smooth going it answers very well and does away with the necessity 

 of counting, but on rough land its readings are no guide for distance. 



On simple ground it is generally found that pacing once across each forty acre 

 lot gives sufficient data to map the topography with sufficient accuracy for all 

 ordinary purposes. Elsewhere there may be roads and streams to locate and 

 divides that should be carefully put in. Here the compass and pacing method is 

 still used, tying to the lines as often as may be. Travel in parallel straight lines, 

 is better, however, provided it is sufficient for the immediate purpose in hand. 

 The reasons for this are, first, that it gives more accurate results, and second, that 

 systematic travel of this kind enables the timber land topographer to see a fair 

 sample of all the timber on the land. In times past, one of the principal reasons 

 for the notoriously inaccurate estimates given by many timber cruisers is that they 

 did not get a fair average of all the timber, which they would have been able to get 

 by travelling along evenly spaced and parallel straight lines running across the 

 tract. 



