Reduction Tables 



Rule. From the line of the given gradient, take out the tabular numbers correspond- 

 ing to each of the figures of the given distance, beginning at the right, and set them 

 down; each one place to the left of the one above it. Retain the ciphers at the beginning 

 of the last tabular number taken out, if any. Other left-hand ciphers may be dropped. 



Add the tabular numbers and point off from the left the number of places equal to that 

 of ihe left-hand figure of the distance, counting: any left-hand ciphers. The result is 

 the difference of elevation, in the same unit as the distance. 



Example: For the diff. of elevation corresponding to a gradient of 5 and a disunre 

 of 6,273 ft., on the slope 



1570 

 S663 

 1047 

 03140 



For 3, opp. 3 and under 3, 

 For 7, opp. 3 and under 7, 

 For 2, opp. 3 and under 2, 

 For 6, opp. 3 and under 6, 

 As 6 is in 4th place, point off 4 

 Diff. of elevation 



(retain leading cipher) 



