  Arkani-Hamed, Dimopoulous, and Dvali have proposed a model of low-scale
quantum gravity featuring large extra dimensions. In this model, the exchange
of Kaluza-Klein towers of gravitons can enhance the production rate of electron
and photon pairs at high invariant mass in proton-antiproton collisions. The
amount of enhancement is characterized by the parameter $M_S$, the fundamental
Planck scale in the bulk extra dimensions. We have searched for this effect
using 100 pb$^{-1}$ of diphoton data and 110 pb$^{-1}$ of dielectron data
collected with the Collider Detector at Fermilab at $\sqrt{s}=1.8$ TeV during
the 1992-1996 run. In the absence of a signal, we place 95% confidence-level
limits on $M_S$ of 905 GeV/$c^2$ and 826 GeV/$c^2$, for the case of
constructive and destructive graviton interference respectively.
