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MENSURATION AND SURVEYING 



2. Liquids in communicating vessels are on a level. 



A B 



A and B are two glass j 



vessels or bottles connect- J- 



ed by a tube AB, contain- 

 ing some coloured liquid 

 and mounted on a stand 

 CD. 



3. Instead of a mason's level a bubble tube placed on a 

 plank with parallel edges may be used. 



The following simple example shows the use of the Dumpy 

 level. 



It is require d to find the difference in level between 

 stations (1) and (3). Erect the spirit level at A and take the 

 - backsight " re ading on the staff at (1) and the " foresight" 

 on the staff at ( 2). Then move the level to B and repeat the 



