A procedure is derived for obtaining low -resolution
spectrophotometry of quasars directly from the objective -prism plates
on which they were discovered. Measurements with a PDS
microdensitometer of - 130 quasar candidates in approximately the
central 19 square degrees of the UK Schmidt prism plate UJ3682P were
used in the application of the procedure (practical details of the
searches for quasars and of the objective -prism spectrophotometry are
given). The success of the objective -prism spectrophotometry is
demonstrated in a comparison with 12 slit spectra. Redshífts and
equivalent widths can be determined with typical discrepancies of 1%
and 40% respectively.This work on objective -prism spectrophotometry leads to a quantification
of the selection effects that operate in the searches for
emission-line objects on objective -prism plates. The quantification
successfully explains an apparent discrepancy in the detection
efficiencies of the CTIO-4m and Curtis Schmidt surveys for quasars.Spectra of quasars that were observed with the Image Photon
Counting System on the Anglo- Australian Telescope are presented. The
observations of quasars with broad absorption troughs indicate the
ejection of matter with velocities up to ~ 22O00kms⁻¹ and with
velocity dispersions up to -
~ 11000kms⁻¹.Data on the wavelength dependences of the contrast y and the
grain response function g of the Kodak emulsion IIIaJ are presented
