18 EARTHQUAKES. 



its velocity, and other elements connected with the dis- 

 turbance. It will be observed that the design of this 

 apparatus assumes the earthquake to consist of a distinct 

 isolated shock. 



Oldham, at the end of his account of the Cachar 

 earthquake of 1869, recommends the use of an instru- 

 ment based on similar principles. In his instrument 

 four balls like bullets are placed in notches cut in the 

 corners of the upper end of a square stake driven into 

 the ground. 



Vessels filled with liquid. — Another form of simple 

 seismoscope is made by partially filling a vessel with 

 liquid. The height to which the liquid is washed up the 

 side of the vessel is taken as an indication of the intensity 

 of the shock, and the line joining the points on which 

 maximum motion is indicated, is taken as the direction 

 of the shock. If earthquakes all lasted for the same 

 length of time, and consisted of vibrations of the same 

 period, such instruments might be of service. These 

 instruments have, however, been in use from an early 

 date. In 1742 we find that bowls of water were used to 

 measure the earthquakes which in that year alarmed the 

 inhabitants of Leghorn. About the same time the Eev. 

 S. Chandler, writing about the shock at Lisbon, tells us 

 that earthquakes may be measured by means of a sphe- 

 rical bowl about three or four feet in diameter, the inside 

 of which, after being dusted over with Barber's puff, is 

 filled very gently with water. Mallet, Babbage, and De la 

 Beche have recommended the same sort of contrivance, 

 but, notwithstanding, it has justly been criticised as 'ridi- 

 culous and utterly impracticable.' ^ 



An important portion of Palmieri's well-known instru- 

 ment consists of horizontal tubes turned up at the ends 

 * Quai'terly Ttevierv, vol. Ixiii. p. 61. 



