]88 RELATIONS OF SOIL TO HEAT 



of frost described by Galloway is the production of a fine 

 spray of water above the summits of the trees. The orchard 

 is provided with standard pipes, 40 ft. in height, connected with 

 an underground main ; ten of these standards are required 

 for an acre. Each standard terminates above in a cross pipe 

 4 ft. in length, the two ends of the cross pipe being furnished 

 with fine cyclone nozzles turned upwards. The supply of 

 water to the main is made in the watchman's house. As 

 soon as the temperature falls to freezing, an electric alarum 

 rings in the watchman's house, he then turns on the water, 

 and the orchard is presently covered with a fine fog-like 

 mist about 45 ft. above the ground. 



We have already (pp. 160, 163) called attention to the great 

 influence which the neigh bourhood of large masses of water, 

 or the employment of water for irrigation, has in securing 

 immunity from frost. 



