On the one hand, we do not try to confirm that the pure elliptical accretion disk model (Eracleous et al. 1995) is the unique true physical model for the double-peaked emitter 3C390.3. We only use the theoretical disk model to separate the double-peaked broad component from the narrow lines. The properties of the residuals shown in Figure \[res\] for the best fitted results shown in Figure \[3c390\] illustrate that it is one good choice to determine the double-peaked broad component by the theoretical elliptical disk model for the spectra around 1995. On the other hand, although we do not apply the intercalibration method (Van Groningen & Wanders 1992) to correct the effects from small wavelength shifts, different spectral resolutions and different flux scales for different spectra as what have been done in Dietrich et al. (1998), the measured second moment through observed spectrum is accurate and reliable, because the applied broadening velocity in the intercalibration method for 3C390.3 is only ten or more kilometers per second or smaller, which is can be totally ignored for the measured second moment and the corresponding uncertainty of the double-peaked broad H$\alpha$. Thus, the following results based on the measured second moments are reliable.

