Mercy me, I should have returned sooner, methinks--what a scrap! Apparently, I wasn't the only one who'd not heard of it.
Dr. Bill had it right: I meant waterglass, not water glass.
Obviously, he had heard of it. The friend told me he used it to hold cardboard together when he made homemade fireworks many years ago. Now I have a couple more questions about it: was/is it a liquid, paste, or what? And...how did it come to be called waterglass? Oh! Silica...glass; water = liquid; = liquid glass??

I'd never heard of clepsydra, either; thanks for the elucidation, by.

tsuwm: hi! [shy smile e]