AIR AND LIFE. 195 



is transformed into electricity the latter may be stored and kept in 

 reserve, or transferred to a distance to perform 10, 20, 50 miles away 

 any work that may be required. 



Such is, in its main features, M. Plessner's project. Whether it be 

 this or some other which is accepted, there is no doubt as to the neces- 

 sity of trying to utilize a small fraction of the tremendous energy that 

 produces the movements of the atmosphere, and is one of the results of 

 the action of solar heat on our planet. There are certainly many ways 

 in which the problem may be solved. For instance, a very simple 

 method would be the using of wind power to force water into a reser- 

 voir at some height from which it might, at will, be let out to work tur- 

 bines. In mountainous regions, and near the sea, in all places where 

 water and wind are available, this system might be of service, however 

 imperfect it may seem. At all events a great field is open to inven- 

 tors, and a great harvest may be reaped by those who will work it 

 with patience and skill. M. Plessner's investigations will prove very 

 suggestive, and they may also find much that is useful in Mr. S. P. 

 Langley's memoir on The Internal Work of the Wind. The facts re- 

 ferred to by Professor Langley are perhaps of more importance for the 

 problem of aviation, or flight, and for the explanation of the soaring of 

 the larger birds, which all have oftentimes seen sustaining themselves 

 during whole hours, without apparent fatigue, or effort, but they are 

 certainly very suggestive in the realm of aerodynamics. Mr. S. P. 

 Langley has succeeded in proving that the force of the wind is not by 

 any means as constant and uniform as is commonly supposed. It does 

 not impart an approximately uniform movement, but a succession of 

 short, rapid waves or pulsations of varying intensity, and fluctuating 

 in direction on either side of the general course of the wind. He con- 

 siders it as certain that an inclined or suitably curved surface, heavier 

 than air, and free from all attachments whatsoever, may be uplifted and 

 indefinitely supported in the air by means of " internal work," without 

 any further expense of energy than that which is demanded for chang- 

 ing the inclinations of the plane according to the pulsations. It seems 

 quite certain that under special conditions such a plane might advance 

 against the wind, not only comparatively, but in the absolute sense. 

 These data are very valuable, and may prove most useful for practical 



purposes. 



###*## # 



Having considered the general relationship between living organ- 

 isms and the elements, pressure, and movements of the atmosphere, we 

 must now j)roceed to illustrate the relationship between the physical 

 contents of the air and living beings. 



Air contains many elements that are accidental, temporary, and of 

 minor importance. Some are gases; such as, for instance, carbon 

 monoxide, carbureted hydrogen, and many others, for the most part 

 obnoxious and toxic. Of these substances we shall say nothing here, 

 because of their scarcity and irregular occurrence. They are not normal 



