We reinvestigate the low temperature magnetic properties of the ferric wheel, a 10 spin (S = 5/2) iron(III) complex. The energy levels for a Heisenberg antiferromagnet with ten S = 5/2 spins are calculated exactly and found to be in excellent agreement: with the observed low-temperature experimental data. By comparing the low-temperature magnetic susceptibility data with the exact energy levels, a coupling constant of 9.7 cm(-1) is determined.