Who was Dalzell? $\pi$ < 22/7 The Dalzell-Integral reads:
$$0<\int_0^1\frac{x^4(1-x)^4}{1+x^2}dx=\frac{22}{7}-\pi$$
It proves that $\pi<\frac{22}{7}$.
See also Wikipedia.
It was introduced by D.P.Dalzell in 1944 (see Wikipedia).
My question: Who was D.P. Dalzell? Any information on him or her?
 A: In the Paul J. Nahin's book Inside Interesting Integrals, p. 24, it is said

The author of the 1944 paper that first published this gem was D. P.
  Dalzell, a curious fellow who is mostly a ghost in the history of
  mathematics. All of the modern references to Dalzell’s integral make
  no mention of the man, himself, even though he wrote a number of high
  quality mathematical papers and had an excellent reputation among
  mathematicians. Dalzell didn’t help his cause by his habit of always
  using his initials. In fact, he was Donald Percy Dalzell (1898–1988),
  who graduated in 1921 from St. John’s College, Cambridge, in
  mathematics and mechanical sciences. He received an MA degree in 1926,
  and his career was not as a mathematician but rather as a chartered
  engineer (a term used in England for a masters level professional
  engineer). He worked for a number of years for the Standard Telephones
  and Cables Company in London, and had two patents on electrical
  communication cables. The only known photograph of him is the one on
  the MacTutor math web-site (taken at the 1930 Edinburgh Mathematical
  Society Colloquium at St. Andrews).

