carbon data, R = (1.042 ±0.020) -[1.04 ±0.91 (GeV/c 2 )~4]Q w 4 ,giving A + = <*> and A_ = 0.99 GeV/c 2 ; and A + > 1.06 and A_ >0.77 GeV/c 2 at the 95% confidence level.In conclusion, the results of this experiment are in agreement with the predictions of quantum electrodynamics as described by Bjorken, Drell, and Frautschi for the photoproduction of electron pairs.We would like to thank M. D. Rousseau for his invaluable contribution in the early stages of the experiment, and M. W. Collins and A. E. Groome for their excellent support throughout. We greatly appreciate the efforts of A. J. Egginton and the NINA machine group, and the help given by the technical services group under M. J. Moore. Finally, we acknowledge the encouragement and support of Professor A.Inelastic electron-proton scattering at high four-momentum transfer and large electron-energy loss has been used to investigate the electromagnetic structure and interactions of the proton. 1 We have measured the double differential cross section d 2 o{E,E', 6)/dQ,dE' for electrons on hydrogen in a new kinematic region made accessible by the Stanford linear accelerator. We report measurements made at 6° and 10° for several incident energies E, and for a range of scat-dan, and S. C. C. Ting, Phys. Rev. JL61, 1344(1967.

Results of electron-proton inelastic scattering at 6° and 10° are discussed, and values of the structure function W 2 are estimated. If the interaction is dominated by transverse virtual photons, vW 2 can be expressed as a function of w = 2Mv/q 2 within experimental errors for q 2 >1 (GeV/c) 2 and CJ >4, where v is the invariant energy transfer and q 2 is the invariant momentum transfer of the electron. Various theoretical models and sum rules are briefly discussed.