Preliminary results on a measurement of the proton structure function F_2 are
reported for momentum transfers squared Q^2 between 1.5~GeV^2 and 5000 GeV^2
and for Bjorken x between 5.10^{-5} and 0.32 using data collected by the HERA
experiments H1 and ZEUS in 1994. F_2 increases significantly with decreasing x,
even in the lowest reachable Q^2 region. The data are well described by a Next
to Leading Order QCD fit, and support within the present precision that the
rise at low x within this Q^2 range is generated "radiatively" via the DGLAP
evolution equations. Prospects for future structure function measurements at
HERA are briefly mentioned.Comment: 16 pages, with 7 encapsulated figures sent separatel
