POETABLE WIND MOTOKS, ETC. 149 



V. 



PORTABLE WIND MOTORS APPLIED TO 



TRENCHING AND SUBSOILING.* 



BY M. CHAEVET. 



WIND. 



Wind is the more or less rapid movement of translation 

 communicated to different parts of the atmosphere. It is 

 generally assumed that this phenomenon is due to the varia- 

 tions in density of different masses of air under the influence 

 of heat or cold. The air of cool regions travels towards 

 warmer regions, hence those huge currents, some of which 

 are constant and periodical, trade winds; and others, variable, 

 such as those often observed inland. 



The configuration of the country has a powerful influence 

 on the direction of the winds, at least for the lower strata, 

 which alone are utilized by the wind motors in actual use. 

 Mountain ranges, forests, river valleys, break atmospheric 

 currents, and deflect the direction they would follow under 

 the action of the causes which produced them, distributing 

 them in all directions. Therefore, the study of wind currents 

 is a very complex question, when it applies to a large tract 

 of country. If, on the contrary, it is restricted to a small 

 locality it becomes simpler, and may in many cases furnish 

 useful indications for the construction and establishment of 

 wind motors. In a certain spot, every year, at the same 

 time, the winds will recur with the same speed and the same 

 direction, as the obstacles deflecting them remain, and that 

 the causes producing them recur periodically with the 

 seasons. 



It is in this state of variations that agricultural industries 

 must take the wind to utilize it as a motive power. The 

 mechanical arrangements of the motors should be suited to 

 the variations, not only of direction, but also of intensity. 

 As the causes disturbing the equilibrium of atmospherical 

 columns are essentially variable, it naturally follows that 

 the effect, that is to say the rate of speed of the air produc- 

 ing the motive power, is also variable. 



The regions where these motors will be used with the 

 greatest advantage are plains, or summits in hilly countries, 

 sometimes even in certain positions at the entrance or exit 



* Le Progres Agricole et Viticole. Vol. 17, 1892. 



