“Let there be light”*…
From oil lamps to LEDs– the price of light… a larger, interactive version here.
From Max Roser‘s always-illuminating Our World in Data. The underlying research (and methodology) here (pdf).
* Genesis 1:3
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As we switch it on, we might spare a thought for Edward Hibberd Johnson; he died on this date in 1917. Best remembered as a business associate of Thomas Edison (Johnson was president of Edison Electric Illuminating Co., the forerunner of Con Ed, and helped found General Electric), he was an inventor in his own right. Johnson patented a number of lighting devices, especially streetlights, but is surely best remembered as the inventor/creator of the first electric Christmas tree lights– 80 walnut-sized red, white, and blue bulbs strung together– which he displayed in the front window of his New York City home in 1882.
