THE TIDES 107 



of the rigid one by forcing its molecules violently against 

 each other, from within outward. Let this pressure pass 

 a certain mark and we have the phenomenon of an explo- 

 sion, as, indeed, often occurs in the case of fly-wheels. 



These reflections bring out still another radical dis- 

 tinction between my views and those of Newton, namely, 

 that whereas he claims that having once been given its 

 rotation, the earth will continue to rotate forever by sheer 

 inertia, because it cannot stop itself, I hold that the 

 earth, even if it were absolutely rigid and possessed a 

 mathematically spherical shape, would automatically 

 bring itself to axial rest by converting and yielding up its 

 centrifugal force into kinetic energy, or heat, and radiat- 

 ing the same out into space. There simply must be some 

 driving power behind the earth's rotation. What is it? 

 Is it natural or supernatural, mechanical or miraculous, 

 real or imaginary, physical or verbal, inertial or creative ? 

 Calling a fly-wheel persistent will not enable us to dis- 

 pense with the engine, nor will it serve any better for the 

 earth's case. 



The reader will perhaps remember that, in a former 

 chapter, I adopted, as a convenient and sufficiently near 

 standard for the purpose, the sustaining of a ton-weight 

 stationary against gravity as equivalent to one horse- 

 power of energy. Doubtless this is an overestimate of 

 the power, but, if so, it is an error on the safe side and 

 will nevertheless satisfactorily serve our present purpose. 



Let us, then, first inquire how much centrifugal force 

 is consumed by the work of bolstering up the hill of water 

 in the equatorial regions and preventing it from flowing 

 down to the lower level of the arctics ; for the dead weight 

 of this mass answers to the elastic tension of the steel 

 hoop in our former experiment, and since the water is not 

 dammed, power alone will avail to hold it steadily above 

 its natural level. According to the authorities, the weight 

 of the oceans is in round numbers 1,400 quadrillions of 

 tons, of which, let us say, only half is thus energially sup- 

 ported. It follows then, from the premises, that either 

 some 700-quadrillion-horse-power engine which science 

 has as yet failed to locate is spinning our globe round and 



