John Fothergill, M.D., (1712-1780) was one of the best-known physicians in London in the 18th century. He was a botanical collector, a philanthropist, and an active member of the Society of Friends. He entertained and advised a series of young doctors from the American colonies and strove with his friend, Benjamin Franklin, to avert the Revolutionary War, albeit unsuccessfully. A rare glimpse of Dr. Fothergill, the man, and his domestic life is given in the diary of his 17-year-old niece, Betty Fothergill, who spent the winter of 1769-70 in her uncle's household. Excerpts from the diary show him to be a liberal-minded man and one fond of the company of young people; and show Betty to be a sprightly young Quakeress, buffeted by emotional conflicts between loyalty to her north-country fiance and her flirtation with young Dr. John Coakley Lettsom.