Investigations of CP and normal stars with coadded Dominion Astrophysical Observatory spectrograms

The procedures developed at the Dominion Astrophysical Observatory to coadd high dispersion coude spectrograms are described, and an increase in the signal-to-noise ratio in photographic data is shown. These techniques can yield low noise spectra over a considerable wavelength range. Preliminary results of the analyses of such coadditions are shown to demonstrate the power of these procedures.