248 GREENHOUSES 



possible, it may be mixed so dry that it will 

 handle like damp earth. Care must be taken 

 in making this "dry mixture" that every part 

 is moistened. 



Estimating Materials. The quantity of 

 cement, sand and gravel necessary for a giv- 

 en piece of work may be found by multiply- 

 ing the number of cubic feet by the percent- 

 age of cement, sand and gravel in a cubic 

 foot of the mixture to be used. For con- 

 venience these proportions are given in tabu- 

 lar form in terms of barrels of cement and 

 cubic yards of sand and gravel. 



TABLE SHOWING PROPORTIONATE QUANTI- 

 TIES OF CEMENT, SAND AND GRAVEL IN 

 A CUBIC FOOT OF CONCRETE 



Cement Sand Stone or gravel 



Mixture barrel cubic yard cubic yard 



1:2 :4 0.058 0.0163 0.0326 



1:254:5 0.048 0.0176 0.0352 



To use, multiply the number of cubic feet 

 of concrete required by the factor shown in 

 the table. The result will be the quantity of 

 the material required. 



For example, 1000 cubic feet of i :2 14 con- 

 crete would require 



