No, it’s not the name of a law firm. These are old names of occupations. If a census record lists an occupation you are not familiar with, you may have a very interesting ancestor. Coopers made barrels, tinkers repaired pots and pans, and wheelwrights made and repaired wagon wheels. In 1870, my great-great grandfather was listed as a teamster. Does that mean he drove a truck? Of course not, he drove a wagon with a team of horses! What in the world did your ancestor do for a living?