300 RECORD OF SCIENCE FOR 1886. 



what the present writer lias long felt, that the newspaper notices on 

 which so much of our records are based give a very insuflScient idea of 

 the True extent of the area affected, and gives added importance to the 

 work undertaken by the Geological Survey looking to the collection of 

 better records. 



In the ninth volume of the Transactions of the Seismological Society 

 of Japan, Dr. C. G. Knott has a paper on Earthquake Frequency. After 

 a discussion of the probable length of any periodicity which might be due 

 to the gravitational action of the sun or moon, with the result that the 

 periods most likely to be discoverable are semi-anmial and annual, he 

 gives a method of combining the monthly numbers so as to eliminate 

 any shorter periods ; which method he then applies to several earth- 

 quake lists and finds clear indications both of a winter maximum and 

 of a semi-annual periodicity. In regard to the latter, however, the 

 author finds reason to doubt whether it is due to the gravitational cause 

 which led to the search for it. He finds a possible or probable cause for 

 the winter earthquake maximum (which his annual curves show to exist 

 in both northern and southern regions), in the accumulations of snow 

 over continental areas and in the annual change of barometric gradients. 



Ch. V. Zenger, in searching for a possible relation between the cos- 

 mic streams of shooting stars and seismic phenomena, finds the follow- 

 ing results (Compt. Eend., cm, 1288): (1) The days of the passage of 

 the streams and of the solar perturbations coincide with the days 

 of seismic movement during the years 1883, 1884, and 1885, and with 

 volcanic eruptions. (2) When there is a considerable difference between 

 the days of passage of the meteoric stream and the period of the solar 

 perturbations, two groups of seismic movements are observed. (3) 

 These movements are often accompanied by tempests, electric storms, 

 and aurora borealis. 



In a paper by Prof. J. S. ITewberry, reprinted from the School of Mines 

 Quarterly, he advocates the theory of a fluid or viscous interior and a 

 comparatively thin and flexible earth-crust, and that earthquakes are 

 the vibrations attending the folding and breaking of rocks which have 

 been in a state of strain through its gradual contraction. He regards 

 it as quite possible that the provoking cause in any particular case may 

 lie in some comparatively trifling increase of atmospheric pressure or 

 in the transfer of the products of erosion from the land to the bottom 

 of the adjacent sea-basin. 



M. Stanislas Meunier renews his theory of earthquakes (stated in 

 1883), by which he attributes the seismic activity to the effect of 

 water contained in the rocks and suddenly brought under the influence 

 of the internal heat of the earth, the means of its transfer to the super- 

 heated region being the sudden fall of masses of rock already saturated. 

 He finds confirmatory evidence in the numerous shocks characterizing 

 the recent earthquakes in Chios and in Spain. (Compt. Eend., cii, 934.) 



M. Ch. Lallemand presented to the French Academy a suggestion of 



