Re: Is the theory by Jules Verne for the Center of the Earth valid?

Sorry about the delay in answering this query.

Jules Verne was writing at the end of the Victorian Era and many of his 
novels contained "state of the art" information for the time.
There have been great advances in geological knowledge since then. Our 
knowledge of the structure of the Earth is based on the analysis of 
seismic records of earthquakes and underground explosions. This clearly 
demonstrates that the Earth has a core, a mantle and a crust.
 Considerations of the density and mass of the earth suggest that the 
core is made of a heavy metallic element. Iron  is the metal that fits 
this idea best. The core is in two parts: an inner solid core and an 
outer liquid core. Movements within the liquid part create the magnetic 
field of the Earth. 
The mantle is fluid, but because of the immense pressures involved is 
only able to move slowly - think plasticene rather than water! Convection 
currents within the mantle cause the continents to move around. This is 
plate tectonics. In areas (mid ocean ridges and continental margins) hot 
mantle rises closer to the surface and the change in pressure causes the 
mantle material to become more fluid. This may reach the surface as lava 
at a volcano. 
The crust is the part of the Earth that the continents are made of. The 
crust is thin in relation to the mantle and core and floats on the mantle.

Consult any Geology text book for more details.
The book by Arthur Holmes (Principles of Physical Geology) is long in the 
tooth, but is still a very good starting point.