278 ANNUAL OF SCIENTIFIC DISCOVERY. 



or dust accompanying the shock.' we must bear in mind that these are 

 mere accidents, contingent upon the consequences of the principal phe- 

 nomenon, the transit of the earth-wave; namely, upon the disturb- 

 ance of the surface of the land reacting upon its drainage, and produ- 

 cing violent electrical disturbances by friction, by pressure, by changes 

 of temperature, and all these again reacting upon its climate, so as 

 often permanently to affect it." 



In conclusion, Mr. Mallet demies the efficient cause of earthquake- 

 shocks to be a " wave of elastic compression, produced either by the 

 sudden flexure and constraint of the elastic materials forming a portion 

 of the earth's crust, or by the sudden relief of this constraint by with- 

 drawal of the force, or by their giving way and becoming fractured." 



EARTHQUAKES IN 1850. 



VERY severe shocks of earthquakes are described under the date of 

 April 17, as being experienced in Smyrna. They appear to have been 

 felt throughout the whole of the Archipelago, and may be traced to the 

 furthest boundaries of Caramania. 



In the proceedings of the Geological Society of London we find a 

 notice of the occurrence of an earthquake at Brusa, in Anatolia, at 11^ 

 P. M. on April 19, which lasted from eight to ten seconds. The os- 

 cillation seemed to proceed from south to southwest. It was followed 

 by two other shocks during the night, and by four others at intervals 

 up to April 21, all comparatively slight. The same shocks were felt 

 throughout the country as far as Kiutahiyah, and at Kirmasli on Lake 

 Apollonia there was a temporary gush of water and sand from an open- 

 ing in the earth. It was noticed that the strongest shocks followed 

 shortly after heavy hail-storrns ; and also that at Tehekerghe a mo- 

 mentary stoppage of the mineral springs accompanied the shocks. 



A shock of an earthquake was felt at Cleveland, Ohio, and its vicin- 

 ity, on the morning of Oct. 1. The day was clear, and the first indica- 

 tion of the phenomenon was a low rumbling sound, in a northwesterly 

 direction, which increased till it seemed like heavy distant thunder. 

 The earth then exhibited a trembling motion, after which the sound 

 died away. The shock was sufficiently strong to throw crockery from 

 its shelves. 



A letter from Lieut. Maury, dated Dec. 6, says, " Capt. Ballard, 

 of the ship Rambler, reports that at 4 A. M., on Oct. 30, in latitude 

 16 30' N., longitude 54 30' W., he experienced the shock of an earth- 

 quake. On the same day, in latitude 23 30' N., longitude 58 W., and 

 at 4 hours 30 minutes A. M., or, allowing for difference of longitude, 

 44 minutes afterwards, Capt. Potter, in the barque Millwood, expe- 

 rienced a like shock. The ships were about 520 miles apart. Sup- 

 posing them to be in the direct line in which the earthquake was trav- 

 elling,- its rate will appear to be one mile in about five seconds, which 

 is only a little slower than sound (at the rate of one mile in 4.6 sec- 

 onds) travels through the air. It is worthy of note that these two ves- 

 sels were over and in the direction of an elevation, the existence of 

 which my investigations of ocean currents and temperatures have in- 





