Editing Henry Tizard (section)

===Interwar period===
After the end of the war, he was made Reader in Chemical Thermodynamics at [[Oxford University]], where he experimented in the composition of fuel trying to find compounds which were resistant to freezing and less volatile, devising the concept of "[[toluene]] numbers", now referred to as [[octane rating]]s. After that work (largely for [[Royal Dutch Shell|Shell]]), he took up again a government post in 1920 as Assistant Secretary to the [[Department of Scientific and Industrial Research (United Kingdom)|Department of Scientific and Industrial Research]].<ref>{{London Gazette |issue=13630 |date=7 September 1920 |page=2003 |city=Edinburgh}}</ref> His successes in that post (and after promotion to permanent secretary on 1 June 1927)<ref>{{London Gazette |issue=33260 |date=25 March 1927 |page=1959}}</ref> included the establishment of the post of the [[National Physical Laboratory (United Kingdom)|Chemical Research Laboratory]] in [[Teddington]], the appointment of [[Harry Wimperis]] as Director of Scientific Research to the Air Force and finally the decision to leave to become the [[President and Rector of Imperial College London]] in 1929, a position he held until 1942, when he was elected President of Magdalen College, Oxford.

In 1935, the development of radar in the United Kingdom was started by Tizard's [[Advisory Committee for Aeronautics|Aeronautical Research Committee]] (and [[Committee for the Scientific Survey of Air Defence]], which he chaired since 1933) doing the first experimental work at [[Orfordness]], near [[Ipswich]], before moving to the nearby [[Telecommunications Research Establishment|Bawdsey Research Station]] (BRS) in 1936.<ref>{{cite news|last=Celinscak|first=Mark|title="Henry T. Tizard" in Philosophers of War: The Evolution of History's Greatest Military Thinkers|year=2013|publisher=ABC-CLIO|location=Santa Barbara|page=487}}</ref> In 1938, Tizard persuaded [[Mark Oliphant]] at [[University of Birmingham|Birmingham University]] to drop some of his nuclear research and concentrate on development of an improved source of short-wave radiation. This led to the invention by [[John Turton Randall]] and [[Harry Boot]] of the [[cavity magnetron]], a major advance in radar technology, which in turn provided the basis for airborne interceptors using radar.<ref name="GracesGuide">{{cite web|title=Henry Tizard|url=https://www.gracesguide.co.uk/Henry_Tizard|website=Grace's Guide to British Industrial History|publisher=Andrew Ian Tweedie|access-date=23 August 2017}}</ref>