OUTDOOR SWIMMING POOLS 



be built under them. If the earth walls stand firm 

 up to the ground level, only inside forms will be 

 needed. In cutting the two-by-fours remember that 

 the walls are carried three feet above the ground. 

 Formerly it was thought necessary to put a fill of 

 rock or gravel as a foundation for the concrete floor. 

 Experience has shown that better results are ob- 

 tained without a fill, provided the bottom of the hole 

 is clay or firm sand and gravel. 



With the forms in place, mix the concrete for the 

 floor of the pool one part Portland cement to two 

 parts sand, to four parts crushed rock. In measur- 

 ing the quantities for each batch, consider one sack 

 of cement equal to one cubit foot. Four parts of 

 clean gravel (sand and pebbles) may be used in- 

 stead of the sand and rock. Have the concrete just 

 wet enough to form a little liquid cement on the sur- 

 face when it is tamped into place. Begin laying the 

 floor in sections, crosswise, at one end of the pool, 

 in the same way as sidewalks are made. Reinforce 

 the concrete two inches from the bottom with one- 

 half inch iron rods, spaced two feet in both direc- 

 tions. Use a wooden float to bring the mortar to 

 the surface, and finish with a steel trowel. 



Immediately thereafter begin on the side walls. 

 For these walls have concrete mushy wet. Fill the 

 one-foot wall space by depositing the concrete around 



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