Oppenheimer was very unhappy at Cambridge and wrote to a friend: "I am having a pretty bad time. The lab work is a terrible bore, and I am so bad at it that it is impossible to feel that I am learning anything." He developed an antagonistic relationship with his tutor, Patrick Blackett, a future Nobel laureate. According to Oppenheimer's friend Francis Fergusson, Oppenheimer once confessed to leaving a poisoned apple on Blackett's desk, and Oppenheimer's parents convinced the university authorities not to expel him. There are no records of either a poisoning incident or probation, but Oppenheimer had regular sessions with a psychiatrist in Harley Street, London. Oppenheimer was a tall, thin chain smoker, who often neglected to eat during periods of intense concentration. Many friends said he could be self-destructive. Fergusson once tried to distract Oppenheimer from apparent depression by telling him about his girlfriend, Frances Keeley, and how he had proposed to her. Oppenheimer did not take the news well. He jumped on Fergusson and tried to strangle him. Oppenheimer was plagued by periods of depression throughout his life, and once told his brother, "I need physics more than friends."