416 KANSAS CITY REVIEW OF SCIENCE, 



but an infinitesimal part of the energy that is constantly being dissipated by the 

 flowing waters of the rivers of the globe. We may safely admit that a large 

 amount of water is constantly needed to water the earth and cause it to bring 

 forth its various vegetable productions for the use of man and beast, but to assert 

 that the larger part of it is ever so utilized is to claim what is not borne out by 

 the facts before us. We are compelled to admit that a large proportion of the 

 force expended in lifting up the waters that form the clouds and that is given out 

 again in the return of these waters to the ocean, serves no practically useful pur- 

 pose in the world, but must be set down as a great and useless waste in the econo- 

 my of nature. 



A like waste of energy is in the movements of the waters of the ocean. This 

 vast collection of water is lifted up on its surface, from a few inches in some local- 

 ities to as much as seventy feet in others, twice in the course of every twenty- 

 four hours. This in mid-ocean is a simple vertical oscillation of the waters 

 through a greater or less space according to the relation of the locality to the 

 position of the Moon. But where it comes in contact with the shores of conti- 

 nents it is greatly modified according to the configuration of the shore line. This 

 variation reaches its maximum in the Bay of Fundy, where the rise and fall often 

 reach from sixty-five to seventy feet. 



Where the shore is low the tide flows out over the land till arrested by the 

 higher ground. At the mouths of rivers it enters and flows back until it has 

 reached its level. The rise and fall, the flow and ebb of these tides are attended 

 with an expenditure of force that is beyond all computation. But notwithstand- 

 ing the immense amount of force involved in the motions of the tides it is almost 

 all uselessly expended so far as appears from a practical standpoint. But the 

 force of waves and currents is not confined to waters of the globe. The great 

 ocean of air that surrounds and envelopes the Earth partakes of like motion and 

 is governed by similar laws. The atmosphere is in almost constant motion, I 

 need not stop here to either prove the fact or to explain the reason. On each 

 side of the Equator for a distance of twenty-five or thirty miles the trade winds 

 blow almost constantly with a velocity of from fifteen to eighteen miles per hour. 

 In other extensive regions there are winds that blow regularly for from six to ten 

 months in the year, while in most other places they are quite variable, but blow 

 from some quarter a considerable part of the time. 



Taking it altogether it is probable the winds that blow over the surface of 

 Earth would equal an average of twenty-five miles an hour constantly over one- 

 half of the earth's surface, A wind blowing with this velocity exerts a pressure 

 of about three pounds per square foot. We know only too well the irresistible 

 energy of the cyclone, the tornado and the hurricane. Nearly all this illimitable 

 force is a useless waste so far as appears to the merely practical mind. 



The last but not least waste of energy to be noted is that which is constantly 

 emanating from the Sun in the form of light and heat. Careful experiment led 

 Sir John Herschel to the conclusion that the heat of the Sun that falls on the 

 Earth is sufficient to melt 26,000 tons of ice per hour for every square mile. 



