Roberts issued a negotiable instrument to Blackmar with a promise to provide Roberts with a complete gym set for use in the basement of his house. Roberts had been looking at this set in a catalog provided by Blackmar for several months, thinking that Blackmar was the sales person for the company selling the gym set. Blackmar in turn signed over the instrument to Upson, who used it to pay for a car he had purchased. Is Roberts liable to Upson, or can he refuse to make good on the note?