Mr. Hume was one of our constant visiters, making, as was the custom of those days, tea-time the hour of calling. In the summer he would often stroll to my father's beautiful villa of North Merchiston. On one occasion — I was then a boy of thirteen—he, missing my mother, made his tea-drinking good with two or three young ladies of eighteen or nineteen, (his acquaintances,) who were my mother's guests. I recollect perfectly how agreeably he talked to them ; and my recollection has been rendered permanent by an occurrence which caused some mirth and no mischief.
When the philosopher was amusing himself in conversation with the young ladies, the chair began to give way under him, and gradually brought him to the floor.
The damsels were both alarmed and amused, when Mr. Hume, recovering himself, and getting upon his legs, said in his broad Scotch tone, but in English words, (for he never used Scotch,) "Young ladies, you must tell Mr. Adam to keep stronger chairs for heavy philosophers."
Quoted from an account by Lord Chief Commissioner Adam in John Hill Burton, Life and Correspondence of David Hume, page 440. Since Adam was born in 1751 this would put the event about 1764; Hume would have been about 53 years old.