Misleading title. He didn't "develop" 120-year-old latent images. This was a developed, stable negative from which he made positive prints.
What's interesting is that 120-year-old image formats, in the form of a photographic negative, can still be read today. Can we feel confident that an Apple HEIC sitting inside an iPhone can be read 120 years from now?
That's why every year I take 50 or so photos and get them printed and bound in a photobook. (There are many vendors that do this, and it's not that expensive.)
What's interesting is that 120-year-old image formats, in the form of a photographic negative, can still be read today. Can we feel confident that an Apple HEIC sitting inside an iPhone can be read 120 years from now?
That's why every year I take 50 or so photos and get them printed and bound in a photobook. (There are many vendors that do this, and it's not that expensive.)