How to sell your book … 200 yrs ago

From “John Dalton – The Father of Chemistry“, on The Science Show:

In an age when science was often the hobby of the wealthy, Dalton made his living by private tutoring and lecture tours. Two famous French scientists came to visit him and were astonished to find him humbly teaching a small boy to read. It has been suggested he was one of the first professional scientists. To one questioner, after a lecture, he is reported to have answered, “I have written a book on that subject, and if thou wishest to inform thyself about the matter, thou canst buy my book for 3/6”.