\chapter*{Summary}
%\markboth{Zusammenfassung}{Zusammenfassung}
\addcontentsline{toc}{chapter}{Summary}

The measurement of the cross section and the extraction of the proton
structure function $F_2$ in the 
kinematical region of $0.2<Q^2<3.5\,$GeV$^2$ for low values of
$10^{-6}<x<10^{-3}$ have been performed. 
The data sample here analysed is a special data period where the
interaction point of the $ep$ scattering was moved from its
nominal position in order to access low values of $Q^2$.

In order to minimize the total error of the measurement, usually two
kinematical reconstruction methods are 
employed, the electron and the $\Sigma$ method. Both methods are
influenced by several systematical errors which uncertainty have to be
quantified.
The present analysis have been investigated the 
uncertainty of the energy measurement of the scattered electron and of
the energy flow of the hadronical final state. 

%In order to minimize the total error of the measurement over the
%accesed phase space, usually two kinematical reconstruction methods are
%employed, the electron and the $\Sigma$ method. Both methods are
%influenced by several systematical errors which uncertainty have to be
%investigated and quantified.
%The present analysis have been investigated the 
%uncertainty of the energy measurement of the scattered electron and of
%the energy flow of the hadronical final state. 
%Therefore a precise calibration of the relevant calorimeters of the
%H1 detector were performed. 

Since after the $ep$ collision for low values of $Q^2$, the electron is
scattered in the backward region of the H1 detector a precise
electromagnetic calibration of the SpaCal calorimeter were
performed. The calibration of the SpaCal calorimeter
used scattered electrons whose energy is localised in the ``kinematical
peak region''. The uncertainty of the energy measurement was found  to
be $0.02\%$ for energies at kinematic peak. The measurement at
lower energies was studied using the reconstruction of the invariant
mass of $\pi^{0}$ decays having an uncertainty of $1\%$. The
correlated error of the $F_2$ measured points, due to the uncertainty
of the energy measurement account to values between $2\%$ and
$4\%$.

In order to extend the measurement to higher values of $x\approx
10^{-3}$, the $\Sigma$ method was used. Using the scattered electron
as the energy scale, the energy flow of the HFS was studied in terms
of their transversal and longitudinal energy. Since
the $\Sigma$ method uses the reconstruction of all particles building
the hadronic final state, detailed studies of the noise and its
influence on the reconstruction of the kinematical variables were
performed. The noise originating from beam or the electronic of the
LAr calorimeter was found to have a negligible influence on the
kinematical reconstruction. The noise substracting algorithm was found
to have an influence of $10\%$ over the accesed phase space.
The uncertainty of the enegy flow identified as coming from the real
ep collision, was asigned to $10\%$ at $y=10^{-3}$ and to $2\%$ at
$y=10^{-1}$, the $10\%$ is mainly coming from the noise identification
algorithm. The correlated error of the $F_2$ measured points, due to
the uncertainty of the energy measurement account to values between
$4\%$ and $8\%$.

