Prof. Cavalleri on a New Seismometer. 103 
known to me, those of Cavalleri I had not heard of, nor yet 
_until recently I was indebted to M. Jeitelles of Kaschau in 
Hungary for acopy of the memoir. I have deemed it worthy of 
translation, partly as my amende to the author for my uninten- 
tional omission of him, and also from the fact that one of his 
arrangements, viz. the pendulums of variable length, is I believe 
new, and that he places some views relative to the movements of 
earth-waves in a clearer light to unmathematical readers than is 
usual. : 
I shall, with your permission, in a future Number of the Ma- 
gazine make some remarks as to the limits of utility of the pro- 
posed instruments, derived from the experience of the actual 
phenomena of shock, obtained in my observation of the earth- 
quake regions of the Two Sicilies early in 1858. 
I am, Gentlemen, yours, &c., 
Monkstown, Co. Dublin, Roserr MALtet. 
January 12, 1860 
Physical science, and geology especially, have long sought for 
a seismometer which should record the shocks and convulsions 
to which the surface of our globe is subject. The various theories 
which have been formed on the origin of earthquakes, and the 
nature of the strata beneath us, are founded on the various 
anomalies and particular effects which earthquakes produce in 
different localities. With the increase of data we have ascertained 
many things relating to physics and geology, many ideas have 
been rectified, and many new ones introduced. We have, indeed, 
several recent works which show a real advance and true scien- 
tific conquest. From the researches of Professor Alfonso Favre, 
made known to us in his two recent works on a hundred earth- 
quakes which occurred in various parts of the world during the 
years 1855 and 1856, not to enumerate other works on the earth- 
quakes of Calabria and Tuscany, it is evident that much light 
has been thrown on the nature of the waves of the terrestrial 
crust when agitated by earthquakes, on their variable rapidity 
and intensity according to the difference of the ground, on their 
refraction and interferences, on their inclination to extend along 
valleys, and in the direction of mountain chains rather than 
across them, and on many other questions no less new than 
interesting. But these ideas and views need much diligent in- 
vestigation before any theory can be formed; and instruments of 
measurement are indispensable. 
Although seismometers may afford us some facility for the 
advancement of science, and may aid in the investigation of these 
difficult questions, yet many, despairing of their success, have 
affirmed that the direct study of the phenomena of the earth- 
