Summary of Delta S Metallicity Measurements for Bright RR Lyrae Variables Observed at Lick Observatory and KPNO between 1972 and 1987

From 1972 to 1987 we conducted a survey of the metallicity of faint RR Lyrae variables in the Galactic halo, using the 'Butler system' of Delta S. As part of the calibration of this program, we made approximately 500 observations of bright RR Lyraes as abundance standards. We summarize all the observations of these bright field RR Lyraes and provide averaged values for the metallicity parameter Delta S. These averages represent the most precise definition of the Butler system for the measurement of RR Lyrae metallicities. The typical mean error is 0.3 units in Delta S, which corresponds to 0.05 dex in (Fe/H). We also briefly discuss the weaknesses in the determination of (Fe/H) from Delta S.