  Ralph Henstock (1923 - 2007) worked in non-absolute integration, including
the Riemann-complete or gauge integral which, independently, Jaroslav Kurzweil
also discovered in the 1950's. As a Cambridge undergraduate Henstock took a
course of lectures, by J.C. Burkill, on the integration of interval functions.
Later, under the supervision of Paul Dienes in Birkbeck College, London, he
undertook research into the ideas of Burkill (interval function integrands) and
Dienes (Stieltjes integrands); and he presented this thesis in December 1948.
  The thesis contains the germ of Henstock's later work, in terms of overall
approach and methods of proof. For example, a notable innovation is a set of
axioms for constructing any particular system of integration. This highlights
the features held in common by various systems, so that a particular property
or theorem can, by a single, common proof, be shown to hold for various kinds
of integration.
  Within this approach, Henstock's thesis places particular emphasis on various
alternative ways of selecting Riemann sums, as the primary distinguishing
feature of different systems of integration. This idea was central to his
subsequent work and achievement.
  Of interest also are those ideas in the thesis which were effectively
abandoned in his subsequent work.
  In addition to Henstock's own insights at that stage of his work, this thesis
provides a good overview of the literature and state of knowledge of
integration of the non-Lebesgue kind at that time.
  These are good enough reasons for transcribing the thesis. Another pressing
reason is that the ink and paper of the near 70 years old copy of the thesis in
the Archive in the University of Ulster Library in Coleraine (Henstock's
personal, annotated copy) are showing signs of deterioration.
  Pat Muldowney February 2017
