VTTLCANOLOGY AND SEISMOLOGY. 4-^1 



$250,000 to $400,000, and the cliurch of San Pedro at Call was wrecked 5 

 November 22, at Lima, Pern, where many bouses were injnred, and August 

 10, in the Eastern and Middle States, when walls were cracked and chim- 

 neys overthrown. Two earthqnakes of the year were made the subject 

 of special study, and maps of the regions affected are given, showing the 

 isoseismals, so fi\r as material for drawing them was at hand. In the 

 earthquake of August 10 the area of greater intensity is nearly ellip- 

 tical, extending from Hartford, Conn., to West Chester, Pa., and the 

 conclusion reached is that this earthquake was due to some rupture of 

 the strata underlying the immediate vicinity of New York City. On 

 September 19 an earthquake occurred in Ohio and Indiana, affecting 

 an approximately circular area with a diameter of about 400 miles. 

 The isoseismals are much more regular in this earthquake than in that 

 of August 10, and its cause is referred to the geological anticlinal 

 known as the Cincinnati arch, which crosses the western part of Ohio 

 from south to north. 



M. C. Detaille has also published {VAstronomie, 1885, p. 183) a list of 

 earthquakes felt in 1884. It gives 165 dates, and is especially rich for 

 ;S()uth American regions, including very careful reports from Valparaiso. 

 It gives reports of 32 shocks at Valparaiso, none of which are contained 

 in Eockwood's nor In Fuchs' lists. In regard to the earthquakes of 

 North America it is much less comj)lete and often inaccurate. 



The catalogue of earthquakes recorded by the Palmieri seismograph 

 at the Imperial Meteorological Observatory in Tokio is contained in 

 vol. VIII of the Transactions of the Seismological Society of Japan. 

 It includes 109 shocks (Nos. 498-60G) on dates between July 28, 1883, 

 and April 25, 1885. For most of them the force and direction is given 

 in Palmieri's scale, with the duration, but without other information. 



The following was compiled from the records of the Meteorological 

 Observatory in Tokio. It gives the total number of earthquakes re- 

 corded in the several months during the ten years ending December 

 10, 1884, as follows : January, 53 ; February, 50 ; March, 73 ; April, 43 ; 

 May, 51 ; June, 40 ; July, 36; August, 27 ; September, 15 ; October, 47; 

 November, 51 ; December, 60. The average per month for the ten years 

 is 45 ; that for the six winter months (October to March) is 50, and that 

 for the six summer months is 35, or about 40 per cent, less, which gives 

 some support to the notion that earthquakes are more frequent in winter 

 than in summer. {Nature, xxxi: 322.) 



The system of seismic observation established in Italy under the di- 

 rection of M. E. de Possi includes twenty-eight stations already in op- 

 eration and reporting to the Central Geodynamic Observatory at Eonie. 

 All are provided with delicate instruments, and study not only the sen- 

 sible earthquakes, but also, and more particularly, those minute move- 

 ments of the ground which are only recorded by the seismograph. 

 These movements are already distinguished into two classes: (1) those 

 characterized by a very rapid vibration; (2) those exhibiting a very 

 H. IMis. 15 31 



