WATER-FILLED BOTTLES + LIGHT
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SPOTLIGHT. In the 1700s, spherical glass bottles filled with water were used to focus candlelight for fine work such as lace making and surgery. -- see "Water sphere lens" https://www.exploratorium.edu/snacks/water-sphere-lens; and see Brian Lemin, "The Great Deception, Lace-makers lamps"
https://www2.cs.arizona.edu/patterns/weaving/webdocs/lb_lamps.pdf
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DIFFUSED LIGHT. In a modern-day emergency, a clear plastic bottle filled with water can be used to diffuse light -- converting a flash light into a lantern which illuminates an area instead of just one spot -- see "Plastic Bottle Lantern" https://www3.nhk.or.jp/nhkworld/en/radio/bosaiweb/craft/craft_20.html
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Sometimes I come across curious tidbits -- like this -- when I'm actively searching for something else. And I'm posting this just in case others might be interested, too.
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QUESTION? I wonder how the many uses of optics and lighting technology developed worldwide? My best guess is that the genesis of this story is probably in Europe.
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QOTO = Question Others to Teach Ourselves?