The curious incident of Wheeler's $\delta$-rays

John Wheeler is well-known for his bold ideas and proposals (``daring conservatism"), which he usually promoted vigorously and repeatedly. Even those that ultimately did not pan out contain important lessons. A curious exception was his idea of so-called $\delta$-rays, which he proposed at the important First Texas Symposium on Relativistic Astrophysics (December 1963). But he did not include this idea in the proceedings of the symposium and apparently never elaborated it subsequently. The only record in print is a one-sentence mention in Hong-Yee Chiu's {\it Report on the Texas Symposium}.\footnote{Quasi-Stellar Sources and Gravitational Collapse, Including the Proceedings of the First Texas Symposium on Relativistic Astrophysics, University of Chicago Press (1965), p. 13} What was that proposal, and why did it quickly disappear from the scene? I will present one record of what Wheeler said at the Symposium.