WASTED FORCES. z 99 



results, and in some countries, notably in Holland, quite extensively. 

 From the best advices I have upon this topic I have it that there are 

 in that country no less than 12,000 windmills, averaging eight horse- 

 power each, giving a total of 96,000 horse-power. 



The chief and obvious difficulties that intrude themselves against 

 the extensive use of the wind as a motive power for general industrial 

 uses are that in most locations it is intermittent in its action, extremely 

 variable as to its power, and quite* unreliable as to the time and dura- 

 tion of its manifestations. 



The immense power stored up in this unfortunately unreliable agent 

 will appear from the statement that a wind of three miles per hour 

 travels 4*40 feet per second, and exerts a pressure of 0*32 to 0*44 pound 

 per square foot of surface opposed to its action. A wind of twenty- 

 five miles an hour, or what sailors would call a good stiff breeze, trav- 

 els 39*67 feet per second, and exerts a pressure of from 2'208 to 3*075 

 pounds per square foot. The prodigious energy of a hurricane, trav- 

 eling not infrequently at the rate of one hundred miles' per hour, is 

 too well known by its disastrous effects to need repetition. The power 

 of the wind, however, save for ship-propulsion, is utilized in but few 

 situations, its unreliability having caused it to be but very slightly 

 esteemed in comparison with water-power and steam. Of late, how- 

 ever, small windmills, especially designed with superior mechanical 

 skill, have been rapidly growing in popularity in this country, mainly 

 for pumping water for railway and domestic purposes, an application 

 for which these devices are excellently adapted; and I entertain no 

 doubt that there are many situations where work is to be done that 

 does not demand a continuous exercise of power, and where the prime 

 consideration to be observed is the element of cheapness, where wind- 

 power might be most advantageously employed. There are, again, 

 extensive regions of the earth, extending for ten or more degrees north 

 and south of the equator, where the winds blow continuously from 

 one direction throughout the greater portion of the year I need hardly 

 remind you that I refer to the region of the " trade-winds," and in 

 which, especially along the coast-line where their influence is not dis- 

 turbed by mountain ranges and other conflicting causes, the force of 

 the wind may be relied upon with almost absolute certainty for the 

 whole or the greater portion of the year. In such regions, therefore, 

 Nature has supplied us with an exhaustless store of energy, capable of 

 meeting the most extravagant demands that may be made upon it. 

 Even the region of the temperate zones, where the winds are variable, 

 our seashores have their strong- land- and sea-breezes which for nine 

 days out of ten may be relied upon; and even in situations where wind- 

 power is most unreliable, as in the interior of the continents, there is a 

 vast and valuable field open for some practical and generally applicable 

 system by which the power of the wind, at present almost universally 

 allowed to go to waste, may be stored up to be given out again as it 



