It was about four years ago that Springer-Verlag suggested that a
revised edition in a single volume of my two-volume work may be
worthwhile. I agreed enthusiastically but the project was delayed for
many reasons, one of the most important of which was that I did not have
at that time any clear idea as to how the revision was to be carried
out. Eventually I decided to leave intact most ofthe original material,
but make the current edition a little more up-to-date by adding, in the
form of notes to the individual chapters, some recent references and
occasional brief discussions of topics not treated in the original text.
The only substantive change from the earlier work is in the treatment of
projective geometry; Chapters II through V of the original Volume I have
been condensed and streamlined into a single Chapter II. I wish to
express my deep gratitude to Donald Babbitt for his generous advice that
helped me in organizing this revision, and to Springer-Verlag for their
patience and understanding that went beyond what one has a right to
expect from a publisher. I suppose an author's feelings are always mixed
when one of his books that is comparatively old is brought out once
again.