During WWII, my Dad worked on a team with James Van Allen & J Allen Hyneck at Johns Hopkins Applied Physics Lab in Silver Spring, MD, building the Proximity Fuse.
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Well, I learned something new. I also learned about the creation of the APL.
http://articles.baltimoresun.com/1993-01-11/news/1993011049_1_fuse-proximity-smart-weapons
Thanks for the link! I’ve passed it along to my sister and my kids, too.
The article mentioned testing it along the Potomac - We have an old photo of my Dad in his surveyor boots and Indiana Jones hat out there at the Aberdeen Proving Ground on the Chesapeake Bay, looking for the place the (non-explosive ) test shells landed.
When I was a kid I had an old peach basket with a table spoon, tin cup, etc to dig in the dirt in my grandmother’s front yard. It also contained one of those non-explosive Proximity Fuses. IIRC, it had a green transparent nose cone, (except the very tip) and the back was a threaded steel tube.