To investigate the underlying structure of matter it is necessary
to have a probe of sufficient resolving power. To do this physicists
have utilized the method of scattering particles from
a target which one wishes to study. The resolving power is
proportional to the absolute value of the four momentum
transfer. In this way it was possible for Rutherford to
establish the existence of a small nucleus inside a
large atom. Subsequent experiments showed that the nucleus
was a bound system of protons and neutrons, collectively called
nucleons.
In 
the first deep inelastic scattering
experiment was performed which for the first time was able
to probe the structure of the nucleon: It was shown to consist
of point-like constituents which were somewhat later identified
as the quarks Gell-Mann and Zweig had proposed to explain
the symmetries observed between hadrons.
A dynamical theory of the interactions of quarks through
a quantized gluon field, Quantum-Chromodynamics ( QCD),
could successfully explain the observed proton structure and
its dependence on the relevant kinematical variables.
With the advent of data from the HERA accelerator the range of the
kinematical variables probed by experiments has increased enormously.
Quark and gluon densities have been measured down to momenta as small
as 
times the proton momentum and to distance
scales as small as 
times the proton diameter.
The proton is now accurately described as an incoherent sum of quarks and gluons, whose momentum density functions obey the QCD prescribed evolutions.
This thesis describes the first observations of charged current deep inelastic scattering using a charged lepton beam. This allows a complementary and independent investigation into the structure of the proton and, more generally speaking, into the interactions between leptons and quarks.