22 



MENSURATION AND SURVEYING 



Co/dents of a stack.— There are two general types of 

 stacks. 



(i) 



(ii) 



\ 



J 



(i) A rectangular parallelopiped and a prismoid. 

 (ii) Two prismoids. 



The weight of straw per cubic yard in the stack varies 

 with the nature of the straw and the length of time it has 

 been in the stack, and the position from which it is taken. 

 Old straw is heavier than new straw and if taken from the 

 bottom of the stack weighs more than that from the top. 



Weight of strav) and examples.- The weight of cholam and 

 paddy straw in the stack is about 124 lb. per cubic yard. The 

 weignt of a stack of hay made at Coimbatore was only 

 88 lb. per cubic yard. 



At these rates the hay will measure 25 cubic yards to the 

 ton, and the straw, 18 yards. 



To set out a right angle with the chain* 



Take 40 links on the chain, 30 links for the perpendicular 

 and 50 for the hypotenuse. 



Obstacles in ranging survey lines. 



1. Seen over and chained round. 



