[gusfoo]

> The cavity magnetron, one of the first practical microwave transmitters, was an invention of such import that it was the UK's key contribution to a technical partnership that lead to the UK's access to US nuclear weapons research.

No, that's not correct at all. The Tube Alloys project[0] was the key, codified in the Quebec Agreement[1], giving the USA access to UK nuclear weapons research.

[0] https://en.wikipedia.org/wiki/Tube_Alloys [1] https://en.wikipedia.org/wiki/Quebec_Agreement

It is an item of some irritation to me that many people think the USA was the nation which started nuclear weapons development first. "In July 1940, Britain had offered to give the United States access to its research, and the Tizard Mission's John Cockcroft briefed American scientists on British developments. He discovered that the American project was smaller than the British, and not as advanced."

[jcrawfordor]

I'm referring to the Tizard mission exactly, in which Cockcroft brought a magnetron to the US for show and tell. Nuclear weapons were less of an emphasis than radar (and jet engines, also a UK-led development) at that point in time.

[aidenn0]

Wasn't the hardened valves for use in fuses also an important part of the Tizard mission?

[jcrawfordor]

Yes! I will draw a slightly roundabout connection here to my pet topics, the British shared a number of fuze concepts as part of the Tizard mission and designs based in large part on the British concepts were developed and tested at the New Mexico Proving Grounds, part of what would later become Kirtland Air Force Base. Much of this work was directed by physicist E. J. Workman, president of the New Mexico School of Mines.

I could probably rewrite the above sentence to improve it, but I focused on the magnetron because it was seen to be of special significance at the time (directly addressed issues that US efforts at e.g. MIT Radiation Laboratory were struggling with) and that there's an interesting story surrounding the couriering of the "most secret" magnetron to the US (it was briefly lost). These were the early days of "classified" as a concept and consistent techniques around safeguarding classified matter hadn't been developed, so the magnetron plays an interesting role there as well (along with documents on a number of topics, but I believe the magnetron was the only "physical artifact" brought by the Tizard mission).