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Yesterday I was certain for most of the afternoon that it was already Friday. |
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Glancing at a clock can make a second seem longer |
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Glance at a wall clock and the second hand sometimes seems to hang there for longer than a second before it ticks on. In 2001, Kielan Yarrow and colleagues put numbers on that in Nature. Volunteers moved their eyes to a target digit that changed as they looked, then judged how long the new digit stayed up. It felt like a full second when it had been visible for only 880 milliseconds after a 22 degree eye movement, and 811 milliseconds after a 55 degree one. The account from inside my field involves saccades, the fast jumps your eyes make when you shift your gaze. Visual input is disrupted during each jump, and the brain appears to extend the new view backwards to just before the movement began. The authors estimated that backdating at about 50 milliseconds, possibly up to 120. Control trials without an eye movement came out close to the true second, and when the target was displaced mid-jump and participants noticed, the illusion disappeared. Describing this as the brain stopping time oversells it, because the measured stretch is roughly 120 to 190 milliseconds. The effect has since been reproduced, including in a 2013 Vision Research study that found it even with simulated eye movements, though each of its experiments used only a handful of participants. A clock is simply the one place where an ordinary brain trick comes with a built-in ruler. |
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Baltimore burned for thirty hours and the hose threads disagreed |
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The Great Baltimore Fire started on a Sunday afternoon, 7 February 1904, and was put out thirty hours later. It destroyed 1,526 buildings across seventy city blocks. Fire companies came from Washington, New York, Philadelphia and other cities, and the National Institute of Standards and Technology records that the hoses of some would not fit Baltimore's hydrants because the threads differed. Others fit. A study by Albert Merrill of the National Bureau of Standards, which became NIST, found about 600 sizes and variations of hose coupling across the country. In 1905 the National Fire Protection Association adopted a standard, with hydrant hose nozzles of 2.5 inches and 7.5 threads per inch. Adoption crawled: by 1914, 287 of 8,000 American cities and towns conformed. A century later, NIST found that only 18 of the 48 most populated American cities had hydrants with both connections complying with the national standard. |
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Mexico City sinks by up to 50 centimetres a year |
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In places, Mexico City drops by as much as 50 centimetres a year. The ground under it is the bed of Lake Texcoco, where the Aztec capital Tenochtitlán once stood, and AGU's Eos magazine describes it as about 100 metres of salty, clay-rich sediment. In 2021, Chaussard and colleagues combined 115 years of levelling surveys with 24 years of satellite radar and 14 years of GPS data. Rates have been mostly constant since at least 1950. The sinking area matches the extent of the old lake, and the rate rises with the thickness of the clay-rich upper layer, which the paper calls the upper aquitard. The authors judge most of it irreversible, and the title of their Journal of Geophysical Research paper says so: "Over a Century of Sinking in Mexico City: No Hope for Significant Elevation and Storage Capacity Recovery." |
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Kodak's 1975 digital camera needed 23 seconds to save one photo |
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In 1975, Kodak engineer Steven Sasson built a camera that, he has said, took 50 milliseconds to capture an image and 23 seconds to record it to the tape. It weighed 3.6 kilograms, about the size of a toaster, and its Fairchild sensor delivered 100 by 100 pixels in black and white. Each cassette held 30 images, and viewing one needed a separate playback unit and a television. Sasson photographed Kodak lab technician Joy Marshall in December 1975. Dark and light shades came out clearly, but the tones between them appeared as static, so her face did not show. Kodak executives watched a few demonstrations and said they saw no market for it, and the camera was never put into production. In 1994 Sasson built the AP NC2000 with Nikon, which IEEE Spectrum describes as one of the first commercially available digital cameras. |
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Twitter turned down the hashtag and users adopted it anyway |
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On 23 August 2007, Chris Messina tweeted: "how do you feel about using # (pound) for groups. As in #barcamp [msg]?" He was proposing a way to group tweets around a common name. According to Euronews, his formal pitch at Twitter's offices was rebuffed. Two days later he wrote that he was "interested in simply having a better eavesdropping experience on Twitter," and Stowe Boyd tweeted support using the word "hashtag" for the first time on Twitter, according to Smithsonian Magazine. The tag first spread widely during the fall 2007 San Diego fires, as #sandiegofire, and by 2009 it was central to protests over Iran's presidential election, according to Smithsonian Magazine. As office pitches go, this one worked by going round the office. Messina told Euronews in 2017 that hashtags got in as "kind of a trojan horse thing." |
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The Baltimore hydrant is the one I would retell at dinner. |
