ON THE EAETHQUAKE AND VOLCANIC PHENOMENA OF JAPAN. 127 



exploding charges of dynamite, velocities were obtained varying from 

 200 to 630 feet per second. All these experiments were made in 

 alluvium. Amongst other results the following were of importance : — 



1 . The velocity of transit decreases as a disturbance radiates. 



2. The velocity of transit varies with the intensity of the initial 

 disturbance. 



3. The motions transmitted most rapidly are vertical free-surface 

 vibrations ; normal motions come nest, whilst the lowest records obtained 

 were for transverse motions (see 'Trans. Seis. Soc.,' vol. viii. p. 50, &c.). 



Mr. Mallet determined a velocity in sand of 824-915 feet, and in 

 granite, of 1664-576 feet per second. General Abbott, at the destruction 

 of Flood Rock, noted velocities as high as 20,526 feeb per second. 

 Professor S. Newcomb and Captain C. Button determined velocities for 

 the Charleston earthquake of 17,072 feet per second. The highest velocity 

 for a sound-wave through piano steel of density 7 '7 is given by Tomlin- 

 son at 5,198 metres (17,049 feet) per second. 



Although elastic vibrations may have been transmitted from the 

 earthquake district 150 miles to the Tokio Plain at the rate of several 

 thousand feet per second, the resultant gravity-waves in the Tokio Plain 

 itself do not seem to have been propagated at a greater rate than a few 

 feet per second. With these results before us, all we can say is, that 

 earthquakes have caused motions in the ground, which apparently have 

 been transmitted at rates varying between 10 feet per second and 20,000 

 feet per second, the latter being a rate which is higher than that at 

 which sound-waves are propagated through hard steel. Attention has 

 often been called to these facts, but any explanation for them has not yet 

 been formulated. 



The result of Professor Tanakadate's magnetic survey has not yet 

 been published, but I believe he finds that there is a slight irregularity 

 in the curve, showing the daily change in declination, which does not 

 appear to have been noticed before the earthquake. A curious observa- 

 tion, made by Dr. Julius Scriba and other medical men, was that many 

 of the troubles amongst tbe wounded, like tetanus and erysipelas, were 

 in great measure due to the result of nervous excitement. From my 

 own observations at a time when all were camped in the midst of ruin, 

 and every few minutes a shock was heralded by a booming sound, the 

 only effect that the great catastrophe had produced upon the people was, 

 when they heard one of these unaccountable noises, to cause them to act 

 with unusual quickness in seeking safety. Amongst the Japanese, so 

 far as I could learn, there was no hysteria, fainting, or nervous prostra- 

 tion like that which was observed amongst European women. Although, 

 they were surrounded by ruin, the dead, and the dying, all that happened 

 when a hollow thundering announced a coming shock was that they ran 

 quickly for the open, shortly afterwards coming back laughing and 

 talking about the terrible effects of earthquakes. Notwithstanding this, 

 it is not unlikely that this disaster will have produced an impression 

 sufficiently great that for many a year to come it will be commemorated 

 by a religious ceremony, when services will be performed in honour of 

 the dead. 



The Nagoya-Gifu Plain is a flat expanse of rich alluvium, covering 

 an area of about 600 square miles. On its east and west sides it is fringed 

 by low hills made out of tertiary tuffs lying at the feet, pateozoic moun- 

 tains which rise to heights of from 2,000 to 4,000 feet. These latter, 



