Jo Caird at JSTOR Daily:
“‘I have named the paper thus presented Calotype paper on account of its great utility in obtaining the pictures of objects with the camera obscura,’” he said, as quoted by Ellen Sharp, who notes, that “With his improved process, Talbot had reduced exposures from an hour to a few minutes, or even seconds, depending on the strength of the sun.”
Rather than offering this discovery (what Geoffrey Belknap, head curator at the UK’s National Science and Media Museum, has called “a critically important innovation in photographic history”) to the world for free, Talbot took a different approach. Just as Daguerre had done, Talbot took out a patent on the calotype process, hoping to earn a living in perpetuity from his ingenuity.
more here.