3 oo THE POPULAR SCIENCE MONTHLY. 



may be required for service; for it may be made to coil a spring, to 

 raise heavy weights, or lift water into elevated reservoirs, or, by other 

 simple devices well known to the mechanical engineer, to store up its 

 power, which may be subsequently given out through machines espe- 

 cially adapted for the purpose. 



The tides ebbing and flowing twice daily, lifting upon their bosom, 

 like so many corks, the heaviest vessels, and baffling all efforts to re- 

 strain their resistless force, afford us another instructive topic for 

 consideration in treating of the wasted forces of Nature for here, 

 again, she has lavished out of her superabundance infinitely more 

 power than any conceivable increase of the needs and industries of 

 man could ever employ. 



The rise and fall of the tides vary, according to local conditions, 

 from a few inches, as in the Mediterranean Sea, to seventy feet, as in 

 the Bay of Fundy, and their force in almost any one of our rivers 

 would, if properly applied, suffice to furnish ample power to all the 

 mills and factories and workshops that could be built side by side 

 upon their banks. They would drive under-shot wheels unfailingly. 

 Where there are extensive meadows regularly overflowed, as they 

 commonly exist along all of our larger streams, a levee containing 

 two sluices, each supplied with a turbine water-wheel, one to be driven 

 by the ebb and the other by the flow, could be made to utilize incal- 

 culable power. 



In some exceptionally favorable localities, where the conditions have 

 forced themselves upon the attention of observing and practical men, 

 tide-motors have been introduced, and with great advantage; but the 

 general utilization of these exhaustless and continuous stores of energy 

 still remains to be accomplished. 



Great rivers above tide-water are rolling down a wealth of power 

 in their currents ; and a hundred factories along their banks, heedless 

 of the fact, are using steam-power. And it is one of the standing 

 marvels that manufacturers fail to recognize the elementary fact in 

 mechanics, that it is not necessary for a stream to have from ten to 

 two hundred feet of fall, in order to do their work ; while the great 

 rivers upon whose banks their workshops are perched are permitted 

 heedlessly to pour out trillions of cubic feet of water, year after year, 

 into the ocean, opposing no mechanical difficulties in the way of yield- 

 ing up their inexhaustible supplies of power. 



Who may estimate the wealth of power poured out in unheeded 

 profusion by our great waterfalls from Niagara down? Confining 

 our attention to the one grand cataract, try to conceive of two mil- 

 lion tons of water per minute hurled down that ledge of rock, rep- 

 resenting 50,000 horse-power expended every minute in the work of 

 disintegrating and undermining the rocky river-bed below. A few 

 tiny paddles, I am told, dip into the current above the falls, and drive 

 a paper-mill, but what of the millions of horse-power that are allowed 



