4 Things We've Forgotten How to Make

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Our knowledge of specific technologies or techniques can sometimes be lost to time. And that can be because of changing economic conditions, or, sometimes, it's because the technology was so deadly that only a few were allowed to know it.

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​​https://www.bbc.com/future/article/20210316-the-legendary-fabric-that-no-one-knows-how-to-make
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https://commons.wikimedia.org/wiki/File:20_to_40mm_recycled_aggregates_(6069277558).jpg
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https://commons.wikimedia.org/wiki/File:Woman%27s_muslin_dress_and_straw_bonnet_c._1830.jpg
https://commons.wikimedia.org/wiki/File:Ancient_Muslin_Depiction.jpg
https://commons.wikimedia.org/wiki/File:Renaldis_muslin_woman.jpg
https://commons.wikimedia.org/wiki/File:Victoria_Memorial_Kolkata_-_Muslin.jpg
https://commons.wikimedia.org/wiki/File:DhakaCity1861.png
https://commons.wikimedia.org/wiki/File:Gossypium_arboreum2.jpg
https://bit.ly/3IVa0nO
https://commons.wikimedia.org/wiki/File:Muslin_men.jpg
https://commons.wikimedia.org/wiki/File:Greekfire-madridskylitzes1.jpg
https://commons.wikimedia.org/wiki/File:Hand-siphon_for_Greek_fire,_medieval_illumination_(detail).jpg
https://commons.wikimedia.org/wiki/File:Arbalest_flamethrower_Greek_fire,_Byzantine_Empire_(reconstruction).jpg
https://commons.wikimedia.org/wiki/File:Trident_warheads.jpg
https://www.flickr.com/photos/kevinpoh/3548617540
https://www.flickr.com/photos/carolemage/12930137013
https://commons.wikimedia.org/wiki/File:Recreated_colored_terracotta_warriors.jpg
https://commons.wikimedia.org/wiki/File:Eastern_Han_Luoyang_Mural_of_Liubo_players.jpg
https://www.mdpi.com/2073-4352/9/5/273/htm
https://commons.wikimedia.org/wiki/File:Tripod_cauldron,_earthenware_with_paint,_Western_Han_Dynasty.JPG
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https://commons.wikimedia.org/wiki/File:British_Museum_Chinese_jade_Han_dynasty_Frog_11022019_1615.jpg
https://commons.wikimedia.org/wiki/File:Eastern_Han_Dynasty_tomb_fresco_of_chariots,_horses,_and_men,_Luoyang_2.jpg
https://commons.wikimedia.org/wiki/File:British_Museum_Bi_Glass_disc_Eastern_Zhou_or_Han_dynasty_11022019_1639.jpg