50 ANNUAL RECORD OF SCIENCE AND INDUSTRY. 



the vibrations of the earth when they were yet too feeble to 

 be appreciated by the human race. In the more important 

 element of the direction from which the shock was received, 

 it appears, by entering these directions upon the map of the 

 region in question, that there is scarcely any rule or regu- 

 larity. 



The most important part of Von Seebach's work consists 

 in the development of the method of investigating earth- 

 quakes by simple observations of the exact moment at which 

 the shocks are felt, a method whose importance was first 

 shown by Schmidt, the director of the observatory at Athens, 

 who, it is stated, deserves the credit of being the first even 

 before Hopkins and Mallet to reduce the phenomena of 

 earthquakes to exact calculations. After having determined 

 the point on the earth's surface directly above the centre of 

 concussion, Von Seebach shows that the mean true velocity 

 of the earthquake shock was 24 English miles per minute, 

 and the depth of the true origin of the shock probably was 

 not less than 7f miles, and not more than llf miles, and that, 

 by reason of our Avant of better observations for the determi- 

 nation of these results, we must assume the depth to have 

 been about 10 miles. Following the example of Mallet, the 

 author attempts also to determine the form of the central 

 cavity within which the explosion took place, and concludes 

 that the cavity lay not far from the village of Amtgaren, ten 

 miles under the surface of the earth, and was very probably 

 a fissure which approximately stretched from N.N. W. to 

 S.S.E., and possessed only slight horizontal dimensions. The 

 fissure was not vertical, but inclined tOAvard the E.N.E. with- 

 in the earth's interior. Von Seebach, Mitteldeutsche Erd- 

 beben. 



EARTHQUAKES IN" THE CAUCASUS. 



Moritz states that the city of Shamaka, in the Caucasus, 

 is so frequently visited by earthquakes, and its inhabitants 

 have so often experienced great visitations, that in that re- 

 gion the words Shamaka and earthquake are synonymous; 

 and yet this is one of the most important and populous 

 cities in the Caucasus. He has, therefore, thought it im- 

 portant to investigate the earthquakes occurring there, in 

 order, if possible, to contribute something to seismic science. 



