532 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 51 



values is 3 



1 n Lo? 4 



*- - «lg 7= ^T— ^- - 1-386 n 

 5 4 Log e 



If n — io 5 then the one-hundred -thousandth part of tdie supply of 

 kinetic energy will be consumed per second and the velocity will 

 fall to one-hali of its original value in 138,600 seconds or 38.5 hours. 

 This might be fairly approximate as to its order of magnitude for 

 cyclones that are on the wane — for we are only endeavoring to get 

 a rough idea of the magnitude of the forces in action. 



The mass of the lowest layer 8 meters deep of the atmosphere 

 is i/iooo of the whole. If we assume its average velocity to be 

 about 1/3 and its energy 1/10 of that of an equal mass of the outer 

 layer then the lowest layer has 1/10000 part of the total energy 

 of the whole moving atmosphere. If the tenth part of this is 

 given up per second to the fixed obstacles that project from the 

 ground [i.e., the smooth oblate spheroid of the geodesists] or to the 

 maintenance of oceanic waves, then this would suffice to withdraw 

 from a cyclone three-fourths of its initial energy in 38 hours. 



If in addition to these there are yet other obstacles to motion 

 still it is probable that these altogether would not cause so great a 

 loss of energy as the pseudo-friction of this lowest stratum. 



3 The notation is lg - Napierian; Log — Briggian. e = Napierian base. 



