TREATING OF CONTRIVANCE 



cept; and in all your works let there be a con- 

 nexion. 



There are some more obstructions in levelling, as 

 in a long walke, when you have the two ends found 

 and marked, either with a supposed or true level, 

 and cannot see betwixt, so as to do it exactly by 

 reason of length : here two may go to the middle, 

 or near it, where you may conveniently see both 

 ends, looking at a distance backward and forward; 

 there drive in two stakes near to the length of the 

 long straight rule, at which hold on the rule, and 

 let one view alongst the same, till the marke at the 

 west-end be level therewith, and likewise the other 

 towards the east, so that both may alter up or down 

 till they have their desires at once. Then fix the 

 rule, and having as many stakes set as is needful, 

 you may view backsight and foresight thereon, and 

 level them all exactly. 



But if a wall, a house, &c., intercept, measure per- 

 pendicular, and exactly up to the top thereof, and 

 on the other side measure down the same again ; 

 and so set forward the level, but so as it may com- 

 municate with the rest when obstructions are re- 

 moved. 



But if a hill, go to the top, set a true level, and 

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