102 Prof. Cavalleri on a New Seismometer. 
in cast iron 11090 feet per second. Making use of this deter- 
mination for want of one more appropriate to the problem, and 
taking c=8956 miles, it will be found that Qe=2,602. This 
= or 2,618, which has been 
assumed in the Theory of the Earth’s Figure solely on the @ pos- 
deriori ground that it gives results in accordance with the observed 
values of the earth’s ellipticity and the precession of the equi- 
noxes. I have gone through the above investigation chiefly for 
the purpose of making the remark, that the assumed relation 
between the density and pressure, and the consequent law of the 
earth’s density, will in a great degree be shown to be physical 
facts, if they bear the test of at once satisfying the observed 
values of the ellipticity, the precession of the equinoxes, and the 
rate of transmission of vibrations through the substance of the 
earth’s crust. In the same degree, a theory of molecular forces 
from which that relation may be antecedently deduced receives 
confirmation. 
If it may be concluded from the foregoing arguments and ap- 
plications of the results, that the theory of molecular forces here 
proposed has a real foundation, what will be chiefly required to 
complete it is to ascertain by analysis the precise composition of 
the functions ~ and qg which have been so frequently referred to. 
Cambridge Observatory, 
January 18, 1860. 
result comes very close to the value 
XIV. Description of a New Seismometer constructed in the Col- 
lege at Monza. By P.G.M.Cavatrert, Professor of Physics 
at the Barnabite College of Monza*. 
[With a Plate.] 
To the Edilors of the Philosophical Magazine and Journal. 
GENTLEMEN, 
fe bases following memoir by Prof. Cavalleri of Monza, although 
in some respects behind the actual state of knowledge, 
may not be unacceptable to English readers interested in seis- 
mology. From the unfortunate condition of Italy, the learned 
of that country know commonly but little of what is doing 
elsewhere in science; and our English libraries are miserably 
supplied with Italian periodical literature. Hence in 1858, 
when in the “Fourth Report on Earthquakes” (Trans. Brit. 
Association) I enumerated and discussed all the seismometers 
* Published at Milan, February 1858. Extracted from the Atti dell’ J. 
R. Instituto di Scienze, Litt. ed Arti, vol. i. part 2. 
