text: Patenting controversy Daguerre's work on his process had commenced at about the same time as Talbot's earliest work on his salted paper process. In 1839, Daguerre's agent applied for English and Scottish patents only a matter of days before France, having granted Daguerre a pension for it, declared his invention "free to the world." The United Kingdom, along with the British Empire, therefore became the only places where a licence was legally required to make and sell daguerreotypes. This exception is now usually regarded as both an expression of old national animosities, still smouldering just 24 years after Waterloo, and a reaction to Talbot's patent. Talbot never attempted to patent any part of his printed-out silver chloride "photogenic drawing" process and his calotype patent was not registered in Scotland.
  In February 1841, Talbot obtained an English patent for his developed-out calotype process. At first, he sold individual patent licences for £20 each; later, he lowered the fee for amateur use to £4. Professional photographers, however, had to pay up to £300 annually. In a business climate where many patent holders were attacked for enforcing their rights, and an academic world that viewed the patenting of new discoveries as a hindrance to scientific freedom and further progress, Talbot's behaviour was widely criticised. On the other hand, many scientists supported his patent and they gave expert evidence in later trials. In addition, the calotype method was free for scientific uses, an area that Talbot himself pioneered, such as photomicrography. One reason Talbot later gave for vigorously enforcing his rights was that he had spent, according to his own reckoning, about £5,000 on his various photographic endeavours over the years and wanted to at least recoup his expenses.