Photography. Supposedly St. Albert the Great was already experimenting with silver nitrate in the 13th century, so it really surprises me that nobody found a way to get a decent image by the end of the Renaissance. Part of me wants to believe that some wealthy collector has unpublished experimental photos taken before the 19th century.
Bicycles. Pic related is was a recreation of a sketch fraudulently attributed to a Da Vinci student. Nevertheless, it certainly would have been well within the reach of preindustrial technology to build something like this.
Microscope. Just how difficult is lens grinding supposed to be, at least to an adequate magnification to see cells? We know the Babylonians were avid astronomers and developed a primitive telescope lens, so it's truly remarkable that they or the Egyptians didn't take the technology further.
>>3348146
Getting a microscope or telescope lens is extremely difficult. you can get an increasing magnification through the lens, but it has to be just perfect in order to actually be able to see anything, and that's where I think it was beyond them. They had the technology to make them, just not the technology to make ones good enough to actually use.
>>3348208
I guess that makes sense. This lens from Nimrud is of clearly dubious value. Some argue it's not even a lens, but a decorative inset in a wooden box which rotted away.
a pre-industrial revolution bicycle would have been shit, and they weren't invented for a reason
>no rubber for the tires so they have to be made out of wood
>the chain and gears would be very difficult to produce and maintain without mass produced identical parts
>turning is next to impossible
its odd to think the bicycle was invented so late, until you think about what its actually made from