Viii PREFACE. 



will be set in forced vibrations by earthquakes and other causes. 

 In fact, the behaviour of the current resembles a piece of india- 

 rubber band, several hundred miles wide, stretched nearly 

 parallel to the coast on the Pacific side. It therefore appears 

 to me that the existence of Kuroshiwo is extremely favour- 

 able to the generation of exciting waves, which spread devasta- 

 tion along the sea coast. 



Thus a portion of my proposals to the Earthquake In- 

 vestigation Committee has been happily brought to a close by 

 the indefatigable zeal of several investigators, who not only 

 prosecuted the observations, but improved the apparatus, deduced 

 corrections to observations, compared the observed with the 

 calculated periods, and solved the important question as to the 

 mode of excitement of oscillations proper to bays and estuaries. 

 It fell to my lot only to guide the method and fix the places 

 of observation, and it is on account of this responsibility that 

 I have allowed myself to add these words as a preface. 



Finally I must not omit to state that my best thanks are 

 due to Dr. B. Mano, the President of the Earthquake Investiga- 

 tion Committee, for allotting during several years a part of the 

 fund granted to the committee for continuing the present research, 

 and the kindly interest with which he has watched the results. 



H. NAGAOKA. 



Physical Institute, Member of the Earthquake 



May 1st, 1907. Investigation Committee. 



