We rarely sees it today, but many people in mid-nineteenth century America, especially those with specialized skills, were proud of their occupations. So proud in fact that they wanted their jobs to be recorded with them in formal portrait photographs. I really can't think of an occupation today, other than sports, where people have their image taken with the tools of their trade or in their occupational garb.
The following are a group of fascinating images from the Library of Congress daguerreotype collection. I'll post more that I found, including some women, in a later post.