ARTICLE PDF RIGHTS AND PERMISSIONS Reprints and permissions ABOUT THIS ARTICLE CITE THIS ARTICLE College of Aeronautics, Bletchley: Prof. W. S. Hemp. _Nature_ 166, 675 (1950).

https://doi.org/10.1038/166675a0 Download citation * Issue Date: 21 October 1950 * DOI: https://doi.org/10.1038/166675a0 SHARE THIS ARTICLE Anyone you share the following link with will be

able to read this content: Get shareable link Sorry, a shareable link is not currently available for this article. Copy to clipboard Provided by the Springer Nature SharedIt content-sharing

initiative