The Switch

what did an hour of this light cost?

one room at night across 3,700 years: hold to work for the same hour of light, and feel the price fall out from under your thumb

The numbers are William Nordhaus's, from "Do Real-Output and Real-Wage Measures Capture Reality? The History of Lighting Suggests Not" (NBER, 1996, nber.org/chapters/c6064), table 1.6: the hours of work that buy 1,000 lumen-hours: an hour of a 1,000-lumen light, or about 50 minutes of a 100-watt filament bulb, which he puts at 1,200 lumens. Sesame lamp, 1750 BC: 41.5. Tallow candle, 1800: 5.37. Whale oil, 1815-45: 4.9. Kerosene, 1875-85: 0.23. Filament bulb, 1950: 0.0019. Compact fluorescent, 1992: 0.00012. The Babylonian row is his own experiment with a Roman lamp and sesame oil, so read it as an estimate; the wages after it are American. A week here means 41.5 hours, a working week by today's count. He also says sesame oil was used in temples and was too expensive for homes, citing a study of later Babylonia (625-400 BC). Old flames are dimmer, so the same light comes thinner, over many nights. Edison's first bulb, 1883, cost more than kerosene (0.75), which the card skips. Whalers going round Cape Horn, voyages of over thirty months by 1848, and whale oil's clean flame with no smell: Bathsheba Demuth, "Harvesting Light", energyhistory.yale.edu. That tallow stank, and the "so" in "so men went to sea", are the card's own shorthand, not his or hers; so is choosing these six rows from his table (tallow fell to 3.0 by 1830; town gas and sperm candles are left out). "It is less now" is our own sum, not his: an LED at about 67 lumens a watt, electricity at about 17.5 cents a kilowatt-hour (EIA, 2025) and the $36.30 hourly wage (BLS, June 2025) come to about a quarter of a second. The hold runs at 7 frames to an hour on every visit, so the times under your thumb are his numbers, to scale.

Concepts: energy, economics.

An interactive you play with one thumb, on Wundr.