PRACTICAL ARBORICULTURE 23 



High mountain - perform the same service, as they become the means of 

 communicating eh ,:ric currents. A plain from which fires have removed all 

 trees and prevented others from growing has not the power of influencing air 

 currents, and, as a rule, clouds pass over them. At long intervals extraordi- 

 nary electrical disturbances occur and moisture is precipitated in unusual 

 quantities during a brief period, causing freshets in valleys which were dry 

 beds a day before. Such storms have been given the term, cloudbursts. 

 Upon Pike's Peak, along the chain of lakes which supply Colorado Springs 

 with water, are telephone lines, as well as telegraph stations. Upon the sup- 

 porting poles, above the wires, is a common barb fence wire, maintained as a 

 lightning arrester. Here on the mountain electrical disturbances are of com- 

 mon occurrence, and it is necessary to provide safety conductors, rain, snow 

 and electric storms being frequent. 



In riding over the divide recently I saw on a small area one hundred prom- 

 inent trees which had received a lightning stroke. High mountains and prom- 

 inent trees are objects which attract the electric current, while the violence 

 with which the disturbance occurs gauges the quantity of moisture precipi- 

 tated, or, in other words, reduces the ability of the atmosphere to hold moisture 

 in solution. 



ELECTRICAL ENERGY. 



The atmosphere is capable of supporting a given weight of water when 

 distributed in minute particles as vapor, the quantity which it can absorb and 

 hold in suspension being variable, depending upon temperature and upon 

 equanimity of electricity, which always accompanies cloud movements. Elec- 

 tricity is rapidly absorbed, conducted and diffused by water. It is transferred 

 through moist air currents to various parts of the earth. Electricity may be 

 passive, as when its changes occur slowly and with regularity, or violent when, 

 by contact with a good conductor, it is suddenly conveyed from cloud to earth, 

 or the reverse. 



Violent electric energy decreases the ability of the atmosphere to retain 

 moisture, and precipitation occurs in great quantities; as these electric changes 

 decrease the power of buoyancy of the atmosphere, a portion of its weight is 

 discharged. 



Heavy clouds hang low upon the surface. The weight of moisture which 

 they bear brings them in contact with objects upon the surface. If these are 

 forests, the electric changes are constant, the regularity causing gentle show- 

 ers. If the obstacle is a prominent tree or spire, the bolt descends, the object 

 is shattered, while a downpour of rain accompanies the violent energy. 



In passing over a mountain chain, abrupt peaks become the conducting 

 medium, and snow is precipitated. 



CLOUDBURSTS. 



This has become a popular expression where extraordinary rainfall occurs. 

 All showers are cloudbursts, simply varying in degree. When more violent 



