On the Origin of Species more recent study by science historian John van Wyhe has determined that the idea that Darwin delayed publication only dates back to the 1940s, and Darwin's contemporaries thought the time he took was reasonable. Darwin always finished one book before starting another. While he was researching, he told many people about his interest in transmutation without causing outrage. He firmly intended to publish, but it was not until September 1854 that he could work on it full-time. His 1846 estimate that writing his "big book" would take five years proved optimistic. An 1855 paper on the "introduction" of species, written
On the Origin of Species it made more widely available; the price was halved to 7s 6d by printing in a smaller font. It includes a glossary compiled by W.S. Dallas. Book sales increased from 60 to 250 per month. In the United States, botanist Asa Gray, an American colleague of Darwin, negotiated with a Boston publisher for publication of an authorised American version, but learnt that two New York publishing firms were already planning to exploit the absence of international copyright to print "Origin". Darwin was delighted by the popularity of the book, and asked Gray to keep any profits. Gray managed to negotiate