WINTER MEETING. 289 



or 70 feet 8i inches from "A" and "D" shall be the same distance 

 from " B." Xow we have a perfect square — each corner describing a 

 right angle, and the diagonals are 45° from the boundary lines. 



Having established a point for a tree, corner-stone or other object 

 requiring an excavation to set it, the point may be held as follows : 



Take a strip board with one straight edge. Bore a hole through 

 each end. Cut a notch near the middle of the straight edge. Put the 

 notch at the point. Drive a stake through each hole and into the 

 ground. 



Now lift the board off of stakes and make the excavation. Now 

 set the board again with the stakes through the holes. The notch will 

 still indicate the point. Should the tree or other object be large, the 

 board may be staked so that the notch is to one side of the point any 

 given distance, say four or five inches. 



It is occasionally desirable to know how to measure the distance 

 across a stream or from one hill top to another. 



Set point "A" on one bank. On opposite bank set point " B." 

 From "A" lay off a line 45° from line "A" "B." Produce this line by 

 sighting across the stream and setting point "C." Now the line "A" 

 "C" and "A" "B" describe a 45° angle at "A." Now cross over to 

 "B" and stake off a line at right angles to "A" " B." Produce this 

 line until it intersects "A" " C." From this point of intersection to 

 "B" the distance is the same as the line "A" " B," because "A" "B" 

 and " B " " C " describe two sides of a square. 



Here is another method: Set point "A." Let "B" represent 

 point on opposite side of stream, or on a distant hill or mountain, and 

 it is required to know the length of the line "A" " B." From "A" lay 

 off a line any distance at right angles to "A" " B," and set " C." Come 

 back to "A" and measure in opposite direction from "B " any distance 

 and set "D" in line with "A" "B." Now lay off a line parallel with 

 "A" " C " and, of course, at right angles lo " D," "A," " B." Produce 

 this parallel line until a point is reached on a line with " B " " C," and 

 set "E." Measure from "D " in the direction of " E" the same dis- 

 tance as " C " is from "A" and set " F " on the line " D " " E." 



Of course, the distance from "C" to "F" is the same as from "A" 

 to "D" and from "E" to "F" is the difference between "D" "E" and 

 "A" "C." 



Then "B" F" is to -'C" "F" as "A" C" is to "A" B." Suppose the dis- 

 tance from "A" to "C" is 40 and from '-D" to "E" 70 and from "A" to 

 '•D" 60. Then "E" "F" would be the difference between "D" "E" and 



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