Notices of Memoirs — Pi^of. J. Milne — Earthquahes in Japan. 465 



11. — Earthquake Phenomena in Japan. Twelfth Eeport. By 

 Prof. John Milne, F.R.S., F.G.S. 



1. The Gray- Milne Seismograph. 



THE seismograph constructed in 1883 — the expense of which was 

 partly defrayed by the British Association — has during the 

 last year given diagrams and records of Earthquakes, from number 

 1106 to number 1241. 



2. Report on Earthquakes felt in Japan in 1888 and 1889. 



In 1888 the number of Earthquakes recorded in Japan was 630, 

 and the total land area shaken was 970,800 square miles. In 188t> 

 the number of Earthquakes was 930, and the area shaken 1,048,200 

 square miles. On February 5th, 1888, an Earthquake shook 57,600 

 square miles. Some accoant is given of Earthquakes which preceded 

 the eruption of Bandaisan, when within 10 minutes 28 square miles 

 of a fertile valley were buried from 30 to 100 feet deep beneath a 

 sea of earth and boulders. Everybody in the district perished. The 

 damming up of the valley has formed a lake 8^ miles long. 



On July 28th, 1889, an Earthquake took place in the Southern 

 island. Twenty were killed and seventy-four wounded. All these 

 Earthquakes have been classified with regard to hours, days, months, 

 seasons, etc. They are also grouped according to intensity, direction, 

 etc. It is clear that the vast amount of material which comes in 

 yearly from the 700 stations of observation is capable of being analysed 

 hj methods other than those given. The Government Staff is 

 insufficient to carry out more than their usual routine work. To 

 carry it out privately requires access to documents and funds. The 

 nature of new researches which might be made is indicated in the 

 Eeport. At any moment all this valuable material bearing on 

 Seismology accumulated in Japan, and of which there is no copy, 

 may be lost by fire. 



3. Earth Pulsations. 

 So far as the writer is aware, no attempt has been made to 

 determine the character of the movements common to all countries 

 usually called Earth Tremors. By using exceedingly light conical 

 pendulums (made from a needle and a silk fibre) — the pointer being 

 replaced by a small mirror reflecting a ray of light — the writer is 

 inclined to the view that the earth-motions producing movements in 

 this form of apparatus are not elastic vibrations such as might be 

 produced by the beating of a steam hainmer, but that they are long 

 wave-like undulations like the swell on an ocean. During the time 

 that these pulsations are continuing it is noticed that they have a 

 definite direction. They are most frequent when the place of 

 observation is crossed by a steep barometric gradient, whether there 

 is wind or whether it is fine. The possible relationship of these 

 movements to the escape of Fire Damp, the swinging of pendulums, 

 etc., is discussed. The records of these phenomena have been 

 photographed, and examples of them accompany the Eeport. 



DECADE III. — VOL. IX. NO. X. 30 



