Victoreen! I remember those!
They were yellow, like the signs.
Yes and in my book, they show you how to make one out of household materials.
A person needs to know the dose you get when you go out even after a week or so.
The measure from the time we started setting off above ground nuke tests to the time it took to show up in the well water.
Now to be sure..it depended on the depth and distance etc. But it gave them a rough idea.
One more Tom.
Know what it taste like? An elder Japanese guy I watched on a special one time said it tastes like chewing on tinfoil.