  We have proposed that the cosmic ray spectrum "knee", the steepening of the
cosmic ray spectrum at energy $E \gsim 10^{15.5}$ eV, is due to "new physics",
namely new interactions at TeV cm energies which produce particles undetected
by the experimental apparatus. In this letter we examine specifically the
possibility that this interaction is low scale gravity. We consider that the
graviton propagates, besides the usual four dimensions, into an additional
$\delta$, compactified, large dimensions and we estimate the graviton
production in $p p$ collisions in the high energy approximation where graviton
emission is factorized. We find that the cross section for graviton production
rises as fast as $(\sqrt{s}/M_f)^{2+\delta}$, where $M_f$ is the fundamental
scale of gravity in $4+\delta$ dimensions, and that the distribution of
radiating a fraction $y$ of the initial particle's energy into gravitational
energy (which goes undetected) behaves as $\delta y^{\delta -1}$. The missing
energy leads to an underestimate of the true energy and generates a break in
the {\sl inferred} cosmic ray spectrum (the "kne"). By fitting the cosmic ray
spectrum data we deduce that the favorite values for the parameters of the
theory are $M_f \sim 8$ TeV and $\delta =4$.
