Cool to see how much engineering relied on intuition and improvisation before modern tools existed. These methods look primitive now, but they worked because people understood materials so well. Makes me wonder how much of that hands-on knowledge we’re losing today.
There are 2 in quick succession in Marple ([1] and [2]), very near the Marple Lock Flight ([3]). This happens to be at the very start of Macclesfield Canal.
This article seems to focus mainly on Western civilization. Not saying they aren't wonders. There were many engineering feats in the South/East Asian subcontinents that are not covered.
When visiting Bath[1] in UK (mentioned in the article), I learned the Romans used a clever contraption, the "three legged lewis", to lift heavy stones[2].
Referring to the diagram[3] on Wikipedia, a concave hole is first cut into the stone. Parts 1 and 2 of the lewis are inserted, one at a time. Inserting part 3 between 1 and 2 results in all three locking into place. A pin and ring at the top keeps the 3 parts from separating.
Though really amazing engineering, I'd say not all of them show "how they pulled it off". I'd like to know how the Byzantine geared mechanical calendar was "pulled off", especially those gears.
Quibble: I hate, despise, loathe the dilution of the word "rare" to mean, well, in this case "somewhat interesting and not commonly known".
Photos cannot be rare. Physical copies of a photograph might be. Photos are by their nature singular instances of artistic or technical action, so all of them are equally rare.
If you liked the Snake Bridge, check out US 441 as it passes (around itself) through Great Smokey National Park (Newfound Gap). The road literally underpasses itself in a very tight loop.
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[ 7.5 ms ] story [ 66.5 ms ] threadhttps://www.google.com/maps/place/Spiral+Bridge/@53.2849203,...
https://www.google.com/maps/place/Spiral+Bridge/@53.2850202,...
[1] https://maps.app.goo.gl/tYBvtfJwSSo6nBm29
[2] https://maps.app.goo.gl/nYoCxPmDRpM9ADfFA
[3] https://en.wikipedia.org/wiki/Marple_Lock_Flight
Referring to the diagram[3] on Wikipedia, a concave hole is first cut into the stone. Parts 1 and 2 of the lewis are inserted, one at a time. Inserting part 3 between 1 and 2 results in all three locking into place. A pin and ring at the top keeps the 3 parts from separating.
[1] https://www.romanbaths.co.uk
[2] https://bathgeolsoc.org.uk/journal/articles/2021/2021_Moving...
[3] https://en.wikipedia.org/wiki/Lewis_(lifting_appliance)#/med...
Photos cannot be rare. Physical copies of a photograph might be. Photos are by their nature singular instances of artistic or technical action, so all of them are equally rare.
[•] https://www.loc.gov/pictures/resource/hhh.tn0278.photos.3658...