CONSTRUCTION NOTES 



379 



to hold the sprinkler and hose not far from the ice, going back and forth, 

 often on the run, so as to catch the previous strip of water before it freezes, 

 and another man to keep the hose in proper position behind the man handling 

 the sprinkler. When the entire area has been covered, go through the whole 

 process again if the first coat is frozen. If not frozen, wait until it is. If 

 more than the thinnest film of water is put on to the foundation surface it 

 will soak through or out at the bottom and leave a white glassy shell. 

 Warm water is better to spray with than cold water. The amateur notion 

 that spraying into the air will cool the water and hasten its freezing is 

 erroneous. Crystallization sets in more quickly if the water is warm. Warm 

 water melts, levels and smooths better, but it must be put on thin. Any 

 approach to flooding will produce shell ice. The ice must be kept clear of 

 twigs, grass and dust, and must be swept clean before a frosty night, whether 

 sprayed or not. Skate snow, if left to evaporate, rots the ice. With the 

 thermometer about ten degrees above zero, the best time to spray is after 

 sun-up, about seven or eight o'clock in the morning. A temperature much 



PLATE No. 171 

 SKI SLIDE, GORDON PARK, BOARD OF PARK COMMISSIONERS, MILWAUKEE, WISCONSIN 



